Daughter's math homework (1 Viewer)

[P Boy]

So who should I get to design and engineer my depression in the ground, Smoo or PonyBoy, or both? Up to now I've just been getting by on whatever indentation my massive ### makes.

I can personally guarantee that if I engineer your depression in the ground that it won't fail, and I've got the insurance to back it up! Of course, I will have to charge you serious jack to do the work...

 

[Gamblor]

For all those that think Dr. Math is supporting them that both are correct here is another post which disputes that...

Even larryboy cant argue with this logic.

http://mathforum.org/library/drmath/view/57375.html

Order of Operations: Negative Sign, Parenthesis

Date: 8/25/96 at 10:6:23

From: Doug Young

Subject: Meaning of Negative Sign, Parenthesis

Dear Dr. Math,

Every school year my students have a hard time seeing

(-2)^2 = 4 and -2^2 = -4. They do not see the need for the

( ) and see -4 as a negative number taken to the 2nd power.

I have tried to show them -1 * 2^2 = -4 is what is being stated

when they see -2^2 = -4. Any suggestions?

Thank you,

Mrs. Young.

Date: 8/25/96 at 15:30:58

From: Doctor Robert

Subject: Re: Meaning of Negative Sign, Parenthesis

I think that all students have trouble with this one. You have

shown them that -2^2 means -1 * 2^2. What you need to convince

them to do is to use the ORDER OF OPERATIONS correctly.

The exponent must be dealt with before the multiplication by -1.

This is not a law of God, but an international agreement among

mathematicans.

Good luck.

-Doctor Robert, The Math Forum

Check out our web site! http://mathforum.org/dr.math/

 

[P Boy]

Tonight, on the FFA:Geeks gone bad. The sad but true stories of a really sorry bunch of tools...

 

[Smoo]

You can't convert "... + -5^2" to "... - 5^2" until after you resolve the exponent.

You are completely wrong here.

I'm totally right, because they're different problems.... + -5^2 = ... + 25

... - 5^2 = ... - 25

Very different.

 

[shadyridr]

Precedence of Unary Operators

Date: 09/01/99 at 22:51:05

From: Tyler Longman

Subject: Unary operator precedence / examples

My Dad, who is a programmer, brought up the question of the precedence

of unary operators with respect to what I'm learning in math. The

PEMDAS rule for order of operations ignores unary operators, and my

Dad, despite his trying for several hours, was unable to come up with

a problem that displayed the effects of not giving unary operators

their proper precedence. His knowledge of unary operator precedence

comes from the world of computer programming, not necessarily the same

as in the mathematics world (computer software vendors occasionally

develop their own precedence schemes). Anyway, one list I found showed

unary operator precedence below that of multiplication/division and

above addition/subtraction. But this seems to disagree with what my

Dad believes he was taught in college, namely that unary operators

have a precedence right after that of parentheses. Can you help

explain all of this and maybe give an example showing how ignorance of

the unary operator precedence can cause an incorrect result?

Many thanks,

Tyler

--------------------------------------------------------------------------------

Date: 09/02/99 at 11:59:50

From: Doctor Peterson

Subject: Re: unary operator precedence / examples

Hi, Tyler. Good question. I'm a programmer too, so I appreciate what

you're talking about.

I can easily think of an example, one that we are asked about all the

time:

     -3^2

The negation operator properly has precedence below the exponential,

so that this means

     -(3^2) = -9

rather than

     (-3)^2 = 9

We don't usually list unary operators in PEMDAS because they're

thought of as being implied by the rules for binary operations. You

can think of the minus sign as either subtraction

     -3^2 = 0 - 3^2 = 0 - 9 = -9

or multiplication

     -3^2 = -1 * 3^2 = -1 * 9 = -9

and in either case it has lower precedence than exponentiation, so it

gives the same result. I can't think of any case where it would matter

which of these two latter interpretations we give, that is, any case

where giving "-" an additive precedence or a multiplicative precedence

will make a difference in the result; commutativity and distributivity

seem to take care of that. For example,

     (-2) * 3

(putting negation at the same level as multiplication) is the same as

     -(2 * 3)

(putting it after multiplication). But certainly negation must not

have a lower precedence than addition, because then

     -2 + 3

would mean

    -(2 + 3)

which is so contrary to sense that it's hard to imagine doing it.

When negation is listed in the order of operations, it's commonly put

with or just above the multiplicative operators. After all, it is

essentially a form of multiplication.

You're right that each programming language defines its own

precedence; they generally try to follow tradition, but there can be

special issues that force them to modify it. Here's the list for C:

     () [] . ->           ("primary expression operators")

     * & - ! ~ ++ --      (unary operators)

     * / %                (binary operators: multiplicative)

     + -                  (additive)

     >> <<                (shift)

     < > <= >=            (comparison)

     == !=                (equality)

     &                    (bitwise and)

     ^                    (bitwise exclusive or)

     |                    (bitwise or)

     &&                   (logical and)

     ||                   (logical or)

     ?:                   (ternary operator: conditional)

You see that C does put unary operators right after parentheses; but

since there is no exponent operator, this doesn't conflict with my

rule.

You may be interested in this page I ran across, on the order of

operations in Microsoft Excel. It says that they evaluate unary minus

before exponentiation, and will not change it though they acknowledge

that this is different from the normal order:

   http://support.microsoft.com/support/kb/ar...s/q132/6/86.asp  

- Doctor Peterson, The Math Forum

  http://mathforum.org/dr.math/  

Here's clear proof that Excel acknowledges that they do it wrong.

 

[John 14:6]

- 5^2 <> -5^2

I don't think spaces have any meaning in math...

Then why use them? They were inserted into the last problem for a reason: to separate operators from numbers. So why did the -5^2 not receive the same space? Because the - isn't an operator in that case.

The same reason we use them in programming, it's easier to read.

 

[(HULK)]

This is not a law of God, but an international agreement among

mathematicans.

See. Just because there's an argeement between some people doesn't mean other people can't see it a different way.Its like me thinking torture is a necessity despite the Geneva Convention disagreeing.

 

[Ditkaless Wonders]

So who should I get to design and engineer my depression in the ground, Smoo or PonyBoy, or both?  Up to now I've just been getting by on whatever indentation my massive ### makes.

I can personally guarantee that if I engineer your depression in the ground that it won't fail, and I've got the insurance to back it up!

Of course, I will have to charge you serious jack to do the work...

Insurance. Ah..finally a concept I fully grasp, a deep pocket to sue if need be.

 

[Smoo]

This is not a law of God, but an international agreement among

mathematicans.

Yes, we've established that earlier. Nobody's arguing that the way Clayton and co. are talking about is the way mathematicians have agreed to do it. I'm simply saying it's a non-intuitive, silly, and blatantly anti-integer way of doing it. I'm bravely fighting for the right of an interger, or any number for that matter, to be negative.

 

[Gamblor]

This is not a law of God, but an international agreement among

mathematicans.

See. Just because there's an argeement between some people doesn't mean other people can't see it a different way.Its like me thinking torture is a necessity despite the Geneva Convention disagreeing.

True - anyone can see it in anyway they want. It might be the wrong way, but it is their way.

 

[P Boy]

Now that we have this resolved, can we move forward to fractals & chaos theory?

 

[Clayton Gray]

Please, somebody solve the following problems:

5-*3

12*/4

6+*7

Those don't make sense, right?  You don't put two operators in a row?

So why does this make sense?

0--5

The answer to that is clearly 5.  You're subtracting -5 from 0, to get 5.  Why is that?

Oh right.  Because the negative in front of the 5 is NOT an operator!  It's PART OF THE NUMBER!

Are these statements true?4 x 2³ - 5² = -5² + 4 x 2³

2 x 3² - 6² = -6² + 2 x 3²

Nope. And you don't even have to understand math to see why. On the left side of both, you've separated the negative operator from the number with a space. On the right you've nestled it in right next to the number with no space separator. Why did you do that? Oh, right, because on the right side the negative sign is being used as part of the number, not as an operator.

Oh my.-5² + 4 * 2³ = 4 * 2³ + -5² by the Commutative Property of Addition (a +b = b + a)

4 * 2³ + -5² = 4 x 2³ - 5² by the Definition of Subtracting Integers (add the opposite)

So -5² + 4 * 2³ = 4 x 2³ - 5²

 

[RoarinSonoran]

Now that we have this resolved, can we move forward to fractals & chaos theory?

Didn't we just PROVE chaos theory in this thread?

 

[Gamblor]

Now that we have this resolved, can we move forward to fractals & chaos theory?

One more first - this is kinda fun.For those that think Excel proves them correct, here is an interesting admission of error from Microsoft:

http://support.microsoft.com/default.aspx?...&NoWebContent=1

Formula Returns Unexpected Positive Value

View products that this article applies to.

Article ID : 132686

Last Review : August 15, 2005

Revision : 1.3

This article was previously published under Q132686

On This Page

SYMPTOMS SYMPTOMS

CAUSE CAUSE

WORKAROUND WORKAROUND

MORE INFORMATION MORE INFORMATION

REFERENCES REFERENCES

Microsoft Excel 98 Macintosh Edition Microsoft Excel 98 Macintosh Edition

Microsoft Excel 97 Microsoft Excel 97

Microsoft Excel 7.0 Microsoft Excel 7.0

Microsoft Excel 5.0 Microsoft Excel 5.0

APPLIES TO APPLIES TO

SYMPTOMS

In Microsoft Excel, when you use a minus sign (-) as a negation operator (for example -1) in a formula, the negation operator has higher precedence than a binary operator. This order of precedence may mean that a formula returns a positive value when you expect it to return a negative value. For example, the formula

=-2^2

is evaluated as:

(-2)^2

The minus sign is evaluated as a negation operator. The formula returns a positive value, 4.

Back to the top Back to the top

CAUSE

Microsoft Excel uses an order of calculation to evaluate operators in formulas. The order of evaluation of operators dictates that a minus sign (-) used as a negation operator (such as -1) is evaluated before all other operators. Because of this order, the formula

=-1^2

represents the value -1 squared, and returns the value 1, a positive value.

Back to the top Back to the top

WORKAROUND

To preserve the order of operations in a formula, you can specify that the negative symbol in a formula apply to the entire formula by inserting parentheses around the numbers that you want to be evaluated first.

For example, if the earlier fomula

=-2^2

is changed to

=-(2^2)

the formula returns a negative value, -4.

That has been the standard method for evaluating formulas since the first version of Microsoft Excel.

 

[Smoo]

- 5^2 <> -5^2

I don't think spaces have any meaning in math...

Then why use them? They were inserted into the last problem for a reason: to separate operators from numbers. So why did the -5^2 not receive the same space? Because the - isn't an operator in that case.

The same reason we use them in programming, it's easier to read.

Right. It's easier to read if you separate the numbers from operators. But you didn't do that separation when writing -5. That tells me that you understand that the - in -5 is not an operator, but simply part of the number.

 

[660]

I love non-math people aurguing about trival math. it is funny.

 

[(HULK)]

This is not a law of God, but an international agreement among

mathematicans.

Yes, we've established that earlier. Nobody's arguing that the way Clayton and co. are talking about is the way mathematicians have agreed to do it. I'm simply saying it's a non-intuitive, silly, and blatantly anti-integer way of doing it. I'm bravely fighting for the right of an interger, or any number for that matter, to be negative.

I fully support Smoo here. An negative integer is a number in its own right. Just because a bunch of mathmaticians agree to a certain usage out of laziness doesn't change the fact that the square of a negative number is positive.If you write this: -5

You read it as negative five. Not as 0 - 5.

I find the agreement here to be counter intuitive when applied to an integer.

 

[Smoo]

Please, somebody solve the following problems:

5-*3

12*/4

6+*7

Those don't make sense, right? You don't put two operators in a row?

So why does this make sense?

0--5

The answer to that is clearly 5. You're subtracting -5 from 0, to get 5. Why is that?

Oh right. Because the negative in front of the 5 is NOT an operator! It's PART OF THE NUMBER!

Are these statements true?4 x 2³ - 5² = -5² + 4 x 2³

2 x 3² - 6² = -6² + 2 x 3²

Nope. And you don't even have to understand math to see why. On the left side of both, you've separated the negative operator from the number with a space. On the right you've nestled it in right next to the number with no space separator. Why did you do that? Oh, right, because on the right side the negative sign is being used as part of the number, not as an operator.

Oh my.-5² + 4 * 2³ = 4 * 2³ + -5² by the Commutative Property of Addition (a +b = b + a)

4 * 2³ + -5² = 4 x 2³ - 5² by the Definition of Subtracting Integers (add the opposite)

So -5² + 4 * 2³ = 4 x 2³ - 5²

You also are disobeying the order of operations.

 

[shadyridr]

Now that we have this resolved, can we move forward to fractals & chaos theory?

One more first - this is kinda fun.For those that think Excel proves them correct, here is an interesting admission of error from Microsoft:

http://support.microsoft.com/default.aspx?...&NoWebContent=1

Formula Returns Unexpected Positive Value

View products that this article applies to.

Article ID : 132686

Last Review : August 15, 2005

Revision : 1.3

This article was previously published under Q132686

On This Page

SYMPTOMS SYMPTOMS

CAUSE CAUSE

WORKAROUND WORKAROUND

MORE INFORMATION MORE INFORMATION

REFERENCES REFERENCES

  Microsoft Excel 98 Macintosh Edition Microsoft Excel 98 Macintosh Edition

  Microsoft Excel 97 Microsoft Excel 97

  Microsoft Excel 7.0 Microsoft Excel 7.0

  Microsoft Excel 5.0 Microsoft Excel 5.0

APPLIES TO APPLIES TO

SYMPTOMS

In Microsoft Excel, when you use a minus sign (-) as a negation operator (for example -1) in a formula, the negation operator has higher precedence than a binary operator. This order of precedence may mean that a formula returns a positive value when you expect it to return a negative value. For example, the formula

=-2^2

is evaluated as:

(-2)^2

The minus sign is evaluated as a negation operator. The formula returns a positive value, 4.

Back to the top Back to the top

CAUSE

Microsoft Excel uses an order of calculation to evaluate operators in formulas. The order of evaluation of operators dictates that a minus sign (-) used as a negation operator (such as -1) is evaluated before all other operators. Because of this order, the formula

=-1^2

represents the value -1 squared, and returns the value 1, a positive value.

Back to the top Back to the top

WORKAROUND

To preserve the order of operations in a formula, you can specify that the negative symbol in a formula apply to the entire formula by inserting parentheses around the numbers that you want to be evaluated first.

For example, if the earlier fomula

=-2^2

is changed to

=-(2^2)

the formula returns a negative value, -4.

That has been the standard method for evaluating formulas since the first version of Microsoft Excel.

I was just gonna post that. Logically that means if they admit an error then the correct way of doing it is -5^2=-25

 

[bryhamm]

Wow, 15 pages when the correct answer was provided with the first reply.

 

[(HULK)]

FYI, math transcends any agreed upon usage by a bunch of lazy math nerds.

 

[Smoo]

FYI, math transcends any agreed upon usage by a bunch of lazy math nerds.

 

[Clayton Gray]

-5² + 4 x 2³ = 4 x 2³ + -5²

Now it should be obvious that:

4 x 2³ + -5² = 4 x 2³ - 5² = -7

No no, you've disobeyed the order of operations laws here.You can't convert "... + -5^2" to "... - 5^2" until after you resolve the exponent.

IncorrectInexact

Inexacto

Falsch

Inesatto

Verkeerd

Incorreto

Неправильный

Ukorrekt

不正确

 

[Clayton Gray]

What does this equation equal?

-x^2+x=

if x=5?

Applying the principles I have learned in this thread (Using Claytons et al explanations) I get -20

 

[Ditkaless Wonders]

FYI, math transcends any agreed upon usage by a bunch of lazy math nerds.

Always be nice to eggheads, they control the universe. You don't want to aggravate one and find yourself with a negative credit score, frozen assets, and a criminal history as a pedophile. Aggravating eggheads is like aggravating a chef before he has cooked your food, just plain stupid. Me, I love them. They make my cable work, my walls withstand wind gusts, my water and electricity to flow in and my sewage to flow out, and best of all they leave the hot chicks for the rest of us. What more could you ask? All they ask in return is that we do not give them atomic weggies, pants them in front of girls, nor refer to them as Melvin, except in the unfortunate case where that is actually their name.

 

[Clayton Gray]

- 5^2 <> -5^2

I don't think spaces have any meaning in math...

Then why use them? They were inserted into the last problem for a reason: to separate operators from numbers. So why did the -5^2 not receive the same space? Because the - isn't an operator in that case.

A negative sign is pretty much the same thing as a minus sign.In -5^2, what is in front of the negative/minus sign? Nothing.

What is the number for nothing? Zero.

So -5^2 = 0-5^2.

 

[660]

FYI, math transcends any agreed upon usage by a bunch of lazy math nerds.

Always be nice to eggheads, they control the universe. You don't want to aggravate one and find yourself with a negative credit score, frozen assets, and a criminal history as a pedophile. Aggravating eggheads is like aggravating a chef before he has cooked your food, just plain stupid. Me, I love them. They make my cable work, my walls withstand wind gusts, my water and electricity to flow in and my sewage to flow out, and best of all they leave the hot chicks for the rest of us. What more could you ask? All they ask in return is that we do not give them atomic weggies, pants them in front of girls, nor refer to them as Melvin, except in the unfortunate case where that is actually their name.

Actually as you become an adult you will find that some very smart people, don't fit the nerd mold anymore. But that is when you grow up.

 

[Ditkaless Wonders]

DW will no longer be posting. I have taken over his account as a warning to others. - An egghead

 

[Clayton Gray]

For all those that think Dr. Math is supporting them that both are correct here is another post which disputes that...

Even larryboy cant argue with this logic.

http://mathforum.org/library/drmath/view/57375.html

Order of Operations: Negative Sign, Parenthesis

Date: 8/25/96 at 10:6:23

From: Doug Young

Subject: Meaning of Negative Sign, Parenthesis

Dear Dr. Math,

Every school year my students have a hard time seeing

(-2)^2 = 4 and -2^2  =  -4.  They do not see the need for the

( ) and see -4 as a negative number taken to the 2nd power. 

I have tried to show them -1 * 2^2 = -4 is what is being stated

when they see -2^2 = -4. Any suggestions? 

Thank you,

Mrs. Young.

Date: 8/25/96 at 15:30:58

From: Doctor Robert

Subject: Re: Meaning of Negative Sign, Parenthesis

I think that all students have trouble with this one.  You have

shown them that -2^2 means -1 * 2^2.  What you need to convince

them to do is to use the ORDER OF OPERATIONS correctly. 

The exponent must be dealt with before the multiplication by -1. 

This is not a law of God, but an international agreement among

mathematicans.

Good luck.

-Doctor Robert,  The Math Forum

Check out our web site!  http://mathforum.org/dr.math/ 

That's a different person acting as Dr. Maff. They need to get on the same page.

 

[shuke]

You can't convert "... + -5^2" to "... - 5^2" until after you resolve the exponent.

You are completely wrong here.

I'm totally right, because they're different problems.... + -5^2 = ... + 25

... - 5^2 = ... - 25

Very different.

-5^2 = (-1)*(5^2), and I don't care if you put a + sign in front of it or not.

 

[Clayton Gray]

Precedence of Unary Operators

Date: 09/01/99 at 22:51:05

From: Tyler Longman

Subject: Unary operator precedence / examples

My Dad, who is a programmer, brought up the question of the precedence

of unary operators with respect to what I'm learning in math. The

PEMDAS rule for order of operations ignores unary operators, and my

Dad, despite his trying for several hours, was unable to come up with

a problem that displayed the effects of not giving unary operators

their proper precedence. His knowledge of unary operator precedence

comes from the world of computer programming, not necessarily the same

as in the mathematics world (computer software vendors occasionally

develop their own precedence schemes). Anyway, one list I found showed

unary operator precedence below that of multiplication/division and

above addition/subtraction. But this seems to disagree with what my

Dad believes he was taught in college, namely that unary operators

have a precedence right after that of parentheses. Can you help

explain all of this and maybe give an example showing how ignorance of

the unary operator precedence can cause an incorrect result?

Many thanks,

Tyler

--------------------------------------------------------------------------------

Date: 09/02/99 at 11:59:50

From: Doctor Peterson

Subject: Re: unary operator precedence / examples

Hi, Tyler. Good question. I'm a programmer too, so I appreciate what

you're talking about.

I can easily think of an example, one that we are asked about all the

time:

     -3^2

The negation operator properly has precedence below the exponential,

so that this means

     -(3^2) = -9

rather than

     (-3)^2 = 9

We don't usually list unary operators in PEMDAS because they're

thought of as being implied by the rules for binary operations. You

can think of the minus sign as either subtraction

     -3^2 = 0 - 3^2 = 0 - 9 = -9

or multiplication

     -3^2 = -1 * 3^2 = -1 * 9 = -9

and in either case it has lower precedence than exponentiation, so it

gives the same result. I can't think of any case where it would matter

which of these two latter interpretations we give, that is, any case

where giving "-" an additive precedence or a multiplicative precedence

will make a difference in the result; commutativity and distributivity

seem to take care of that. For example,

     (-2) * 3

(putting negation at the same level as multiplication) is the same as

     -(2 * 3)

(putting it after multiplication). But certainly negation must not

have a lower precedence than addition, because then

     -2 + 3

would mean

    -(2 + 3)

which is so contrary to sense that it's hard to imagine doing it.

When negation is listed in the order of operations, it's commonly put

with or just above the multiplicative operators. After all, it is

essentially a form of multiplication.

You're right that each programming language defines its own

precedence; they generally try to follow tradition, but there can be

special issues that force them to modify it. Here's the list for C:

     () [] . ->           ("primary expression operators")

     * & - ! ~ ++ --      (unary operators)

     * / %                (binary operators: multiplicative)

     + -                  (additive)

     >> <<                (shift)

     < > <= >=            (comparison)

     == !=                (equality)

     &                    (bitwise and)

     ^                    (bitwise exclusive or)

     |                    (bitwise or)

     &&                   (logical and)

     ||                   (logical or)

     ?:                   (ternary operator: conditional)

You see that C does put unary operators right after parentheses; but

since there is no exponent operator, this doesn't conflict with my

rule.

You may be interested in this page I ran across, on the order of

operations in Microsoft Excel. It says that they evaluate unary minus

before exponentiation, and will not change it though they acknowledge

that this is different from the normal order:

   http://support.microsoft.com/support/kb/ar...s/q132/6/86.asp  

- Doctor Peterson, The Math Forum

  http://mathforum.org/dr.math/  

Here's clear proof that Excel acknowledges that they do it wrong.

 

[culdeus]

how is this 16 pages.

 

[Clayton Gray]

This is not a law of God, but an international agreement among mathematicans.

See. Just because there's an argeement between some people doesn't mean other people can't see it a different way.

When you want to learn how to do "Thing A", you generally should accept the rules agreed upon by the experts in "Thing A".

 

[P Boy]

how is this 16 pages.

How is an entire website generating mega-$$$ with thousands of pages dedicated to fantasy football?

 

[Ignoramus]

Holy cow, this thread has legs. Just goes to show how lousy most people are at math, even smart people.

-5^2=x

-therefore-

0=x+5^2

Anyone here still think x=25?

 

[PC Load Letter]

how is this 16 pages.

I asked the same thing.... back when it was 4 pages.

 

[Clayton Gray]

I love non-math people aurguing about trival math. it is funny.

 

[shuke]

Holy cow, this thread has legs. Just goes to show how lousy most people are at math, even smart people.

-5^2=x

-therefore-

0=x+5^2

Anyone here still think x=25?

EXACTLY

 

[Clayton Gray]

Please, somebody solve the following problems:

5-*3

12*/4

6+*7

Those don't make sense, right?  You don't put two operators in a row?

So why does this make sense?

0--5

The answer to that is clearly 5.  You're subtracting -5 from 0, to get 5.  Why is that?

Oh right.  Because the negative in front of the 5 is NOT an operator!  It's PART OF THE NUMBER!

Are these statements true?4 x 2³ - 5² = -5² + 4 x 2³

2 x 3² - 6² = -6² + 2 x 3²

Nope. And you don't even have to understand math to see why. On the left side of both, you've separated the negative operator from the number with a space. On the right you've nestled it in right next to the number with no space separator. Why did you do that? Oh, right, because on the right side the negative sign is being used as part of the number, not as an operator.

Oh my.-5² + 4 * 2³ = 4 * 2³ + -5² by the Commutative Property of Addition (a +b = b + a)

4 * 2³ + -5² = 4 x 2³ - 5² by the Definition of Subtracting Integers (add the opposite)

So -5² + 4 * 2³ = 4 x 2³ - 5²

You also are disobeying the order of operations.

 

[Gamblor]

This is not a law of God, but an international agreement among mathematicans.

See. Just because there's an argeement between some people doesn't mean other people can't see it a different way.

When you want to learn how to do "Thing A", you generally should accept the rules agreed upon by the experts in "Thing A".

It might be kinda fun to disregard the experts' opinions though. I've always kinda thought 4+3 would make a better 20 then a 7.

 

[MrPack]

Tonight, on the FFA:

Geeks gone bad. The sad but true stories of a really sorry bunch of tools...

Holy crap I just spit coffee on my monitor.

 

[Smoo]

-5² + 4 x 2³ = 4 x 2³ + -5²

Now it should be obvious that:

4 x 2³ + -5² = 4 x 2³ - 5² = -7

No no, you've disobeyed the order of operations laws here.You can't convert "... + -5^2" to "... - 5^2" until after you resolve the exponent.

IncorrectInexact

Inexacto

Falsch

Inesatto

Verkeerd

Incorreto

Неправильный

Ukorrekt

不正确

Only according to your arbitrary convention. According to intuition and logic, I am right.

 

[Smoo]

- 5^2 <> -5^2

I don't think spaces have any meaning in math...

Then why use them? They were inserted into the last problem for a reason: to separate operators from numbers. So why did the -5^2 not receive the same space? Because the - isn't an operator in that case.

A negative sign is pretty much the same thing as a minus sign.In -5^2, what is in front of the negative/minus sign? Nothing.

What is the number for nothing? Zero.

So -5^2 = 0-5^2.

This is true if you view the minus sign as an operator. It's not, in this case. It's part of the integer '-5'.

 

[P Boy]

It might be kinda fun to disregard the experts' opinions though. I've always kinda thought 4+3 would make a better 20 then a 7.

Note to Gamblor:Vegas is calling!

 

[Clayton Gray]

how is this 16 pages.

I asked the same thing.... back when it was 4 pages.

Why did you ask about 16 pages when it was only 4?

 

[chet]

Holy cow, this thread has legs. Just goes to show how lousy most people are at math, even smart people.

-5^2=x

-therefore-

0=x+5^2

Anyone here still think x=25?

Please see discussion on whether the - is part of the number or an operator. TIA.

 

[Smoo]

You can't convert "... + -5^2" to "... - 5^2" until after you resolve the exponent.

You are completely wrong here.

I'm totally right, because they're different problems.... + -5^2 = ... + 25

... - 5^2 = ... - 25

Very different.

-5^2 = (-1)*(5^2), and I don't care if you put a + sign in front of it or not.

Nope. Exponents come before multiplication in the order of operations. You cannot factor out the -1 (an act of multiplication/division) until after resolving the exponent.

 

[Clayton Gray]

This is not a law of God, but an international agreement among mathematicans.

See. Just because there's an argeement between some people doesn't mean other people can't see it a different way.

When you want to learn how to do "Thing A", you generally should accept the rules agreed upon by the experts in "Thing A".

It might be kinda fun to disregard the experts' opinions though. I've always kinda thought 4+3 would make a better 20 then a 7.

 

[culdeus]

Just sent this nonsense to my wife's collegue who is the head MathCounts guy in the region and has a PhD from Stanford.

 

[Smoo]

Holy cow, this thread has legs. Just goes to show how lousy most people are at math, even smart people.

-5^2=x

-therefore-

0=x+5^2

Anyone here still think x=25?

-5^2 = x-therefore-

0 = x - (-5^2)

x = 25