2008 AMC 10B Problem 3

Attempt Problem 3 of the 2008 AMC 10B below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2008 AMC 10B solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

3.

Assume that xx is a positive real number. Which is equivalent to xx3?\sqrt[3]{x\sqrt{x}}\,?

x1/6x^{1/6}

x1/4x^{1/4}

x3/8x^{3/8}

x1/2x^{1/2}

xx

Answer: D
Concepts:exponentradical
Difficulty rating: 940
Solution:

Since x=x1/2,\sqrt{x}=x^{1/2}, we have xx=x1x1/2=x3/2.x\sqrt{x}=x^{1}\cdot x^{1/2}=x^{3/2}.

Taking the cube root multiplies the exponent by 13,\tfrac13, giving (x3/2)1/3=x1/2.\left(x^{3/2}\right)^{1/3}=x^{1/2}.

Thus, the correct answer is D.

← Problem 2#2
Full Exam

Problem 3 in Other Years