# Negative even exponents of negative numbers

How can I calculate and prove this equation with mathematical terms: pow((-2), -2)=? I know that pow(1, -1) is equal to 1/1 by the way. Any idea, please?

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## 1 Answer

A negative exponent means taking the reciprocal.

So $(-2)^{-2} = \frac{1}{(-2)^2} = \frac{1}{4}$

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Thank you very much. :) This solves many things actually... – Kerim Atasoy Feb 25 '12 at 11:01
Basically this comes from the way that indices behave under multiplication. We should have (informally) that $a^k \times a^{-k} = a^{k-k} = a^{0} = 1$ so this tells you that $a^{-k} = \frac{1}{a^k}$ (at least for nearly every $a,k$, there are problems with $a$ being 0). – fretty Feb 25 '12 at 11:04
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