I know this is really basic why does

$\displaystyle

f(2)=-4{x}^{-1}$

equal

$\displaystyle

-2$

and not

$\displaystyle -8$

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- Jun 3rd 2009, 05:33 AMEnvySubstituting f(x)
I know this is really basic why does

$\displaystyle

f(2)=-4{x}^{-1}$

equal

$\displaystyle

-2$

and not

$\displaystyle -8$ - Jun 3rd 2009, 05:35 AMProve It
Your question does not make any sense.

Are you asking:

If $\displaystyle f(x) = -4x^{-1}$ what does $\displaystyle f(2)$ equal?

Let $\displaystyle x = 2$.

You would have $\displaystyle f(2) = -4(2)^{-1}$

$\displaystyle = -4\left(\frac{1}{2}\right)$

$\displaystyle = -2$. - Jun 3rd 2009, 05:38 AMJoel
Substituting 2 into the equation

http://www.mathhelpforum.com/math-he...d5227ede-1.gif

-4 * ( 2 to the power of -1 )

2 to the power of -1 is the same as 1 / 2

so -4 * 1/2 = -2 and not -8