Concept

Deriving the Definition of a Negative Exponent Using x2x5\frac{x^2}{x^5}

By simplifying the expression x2x5\frac{x^2}{x^5} using two distinct methods, we can establish the formal definition of a negative exponent. First, applying the Quotient Property for Exponents by subtracting the denominator's exponent from the numerator's exponent yields x2x5=x25=x3\frac{x^2}{x^5} = x^{2-5} = x^{-3}. Alternatively, we can simplify the expression by expanding it and dividing out the common factors: rewriting it as xxxxxxx\frac{x \cdot x}{x \cdot x \cdot x \cdot x \cdot x} allows us to cancel two factors of xx from both the numerator and the denominator. This process leaves three factors of xx in the denominator, resulting in 1x3\frac{1}{x^3}. Since both procedures simplify the identical starting expression, their final forms must be equal, demonstrating that x3=1x3x^{-3} = \frac{1}{x^3}. This comparison illustrates the general rule that a negative exponent signifies the reciprocal of the base raised to the corresponding positive exponent.

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Updated 2026-05-25

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