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Exponent rules

Exponents & logarithms

Japanese school year: Math II

What you learn

Learn how exponent rules extend from positive integers to negative numbers, fractions, and real exponents. These computational rules are fundamental for modeling rapid expansion, exponential decay, and scientific notation in science and engineering. Prior comfort with basic integer powers and polynomial operations will help you master these fractional exponents.

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Key points

This rule states that when multiplying powers with the same base aa, you simply add the exponents mm and nn. For example, 23×24=272^3 \times 2^4 = 2^7.

aman=am+na^m a^n = a^{m+n}

This rule states that when raising a power ama^m to another power nn, you multiply the exponents together to obtain amna^{mn}. It simplifies repeated exponentiation.

(am)n=amn(a^m)^n = a^{mn}

This defines a negative exponent a−na^{-n} as the reciprocal of the positive power, 1an\frac{1}{a^n} (where a≠0a \neq 0). It allows expressions with denominators to be rewritten using exponents.

a−n=1ana^{-n} = \frac{1}{a^n}

This defines a fractional exponent amna^{\frac{m}{n}} as the nn-th root amn\sqrt[n]{a^m} (where a>0a > 0). It enables rewriting radicals in exponential form to apply standard exponent rules.

amn=amn(a>0)a^{\frac{m}{n}} = \sqrt[n]{a^m} \quad (a > 0)

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