Substituting a negative integer for a variable... exponent

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zachres
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Substituting a negative integer for a variable... exponent

Postby zachres » Fri Jun 10, 2011 2:16 pm

I ran across this yesterday in a Pearson intermediate Algebra text.

The problem presented in the text is in regards to graphing ordered pairs. An equation to express the relationship between the pair is given as;

y = 4 - x2

The solution requested is a graph x and y for all pairs where x is an integer from -3 to 3.

For x = -3, the author of the book substituted in this manner;

y = 4 - (-3)2

My question is; why would the substitution not be in this form; y = 4 - (-32)?

The two methods generate different values for x2. The first generates 9, and the second generates -9.

So, again, why one way and not the other?

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Martingale
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Re: Substituting a negative integer for a variable... expone

Postby Martingale » Fri Jun 10, 2011 6:50 pm

zachres wrote:I ran across this yesterday in a Pearson intermediate Algebra text.

The problem presented in the text is in regards to graphing ordered pairs. An equation to express the relationship between the pair is given as;

y = 4 - x2

The solution requested is a graph x and y for all pairs where x is an integer from -3 to 3.

For x = -3, the author of the book substituted in this manner;

y = 4 - (-3)2

My question is; why would the substitution not be in this form; y = 4 - (-32)?

The two methods generate different values for x2. The first generates 9, and the second generates -9.

So, again, why one way and not the other?




is the same as


zachres
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Re: Substituting a negative integer for a variable... expone

Postby zachres » Fri Jun 10, 2011 8:38 pm

Correct, but

-32

is not the same as

(-3)2

At least according to the text;

-32 = 9

(-3)2 = -9

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stapel_eliz
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Postby stapel_eliz » Fri Jun 10, 2011 8:57 pm

zachres wrote:At least according to the text;

-32 = 9

(-3)2 = -9

Then the text has it backwards! :shock:


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