which answer? is f(4) for f(x)=-x**2+5x-7 equal to 29 or -3?

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dianeandjosh
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which answer? is f(4) for f(x)=-x**2+5x-7 equal to 29 or -3?

Postby dianeandjosh » Thu Feb 10, 2011 3:19 am

Given :

f(x) = - x**2+5x-7 notice the - before the first term. This is ambiguous. It is a homework problem.

what is the value of f(4)? is it 29 or -3 ?

snowdrifter
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Re: which answer?

Postby snowdrifter » Thu Feb 10, 2011 4:35 am

dianeandjosh wrote:Given :

f(x) = - x**2+5x-7 notice the - before the first term. This is ambiguous. It is a homework problem.

what is the value of f(4)? is it 29 or -3 ?


The answer is -3.

Here is why:
You function is
this makes

In other words the negative is not part of the variable being squared.
If you were meant to include the negative in the square the function would be:
Then

By the way, the common way of writing using just text is x^2.

SD


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