SAT Math · Equivalent expressions · medium

Which expression is equivalent to x³/2 for x > 0?

Which expression is equivalent to x3/2x^{3/2} for x>0x > 0?

Answer and explanation

Answer: C: √(x³)

A fractional exponent means a root and a power: xm/n=xmnx^{m/n} = \sqrt[n]{x^m}. Here x3/2=x3x^{3/2} = \sqrt{x^3}, choice C. It can also be written (x)3(\sqrt{x})^3. Choice A, 3x1/23x^{1/2}, multiplies by 3 rather than raising to the third power. Choice B, x3x2\frac{x^3}{x^2}, simplifies to xx, which is not x3/2x^{3/2}; subtracting exponents gives 3−2=13 - 2 = 1. Choice D, 2x32x^3, treats the denominator 2 as a coefficient and the numerator as the entire exponent, which is also incorrect. The denominator of the exponent is the root index.

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