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Zero and negative exponents
Practice evaluating numbers and expressions with zero and negative exponents.
Any nonzero number raised to the zero power equals $1$:
If $a \neq 0$, then $a^0 = 1$.
To raise a nonzero number to a negative power, take the reciprocal of the number raised to the corresponding positive power:
$a^{-n} = \frac{1}{a^n}$.
If the base is a fraction and the exponent is negative, take the reciprocal of the fraction and make the exponent positive:
$\left(\frac{a}{b}\right)^{-n} = \left(\frac{b}{a}\right)^n, \quad a \neq 0, \quad b \neq 0$
$\left(\frac{2}{5}\right)^{-3} = \left(\frac{5}{2}\right)^3 = \frac{125}{8}$
A negative exponent does not necessarily produce a negative result. The sign depends on the base and the exponent.
$(-2)^{-2} = \frac{1}{(-2)^2} = \frac{1}{4}$
$(-2)^{-3} = \frac{1}{(-2)^3} = -\frac{1}{8}$
If a negative number is raised to an even power, the result is positive. If a negative number is raised to an odd power, the result is negative. This rule also holds for negative exponents.
First identify the base, apply the zero- or negative-exponent rule, and then simplify the numerical or algebraic expression.
Review the lesson on zero and negative exponents.