Formula

Negative Exponent

A negative exponent indicates that the expression should be rewritten as the reciprocal of the base raised to the corresponding positive power. If nn is an integer and a0a \neq 0, then:

an=1anand1an=ana^{-n} = \frac{1}{a^n} \quad \text{and} \quad \frac{1}{a^{-n}} = a^n

This result emerges naturally from the Quotient Property for Exponents. Consider x2x5\frac{x^2}{x^5}: subtracting the exponents gives x25=x3x^{2-5} = x^{-3}, while dividing out common factors yields 1x3\frac{1}{x^3}. Since both approaches simplify the same fraction, it follows that x3=1x3x^{-3} = \frac{1}{x^3}. In practical terms, a negative exponent instructs you to move the base across the fraction bar (from numerator to denominator, or vice versa) and change the sign of the exponent to positive. An expression containing negative exponents is not considered to be in simplest form.

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Updated 2026-05-14

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