X raised to the power x?

x x 2 3 = x x \large x^{\sqrt[3]{x^2}} = \sqrt{x}^{x}

Find the sum of all real values of x x satisfying the equation above.


The answer is 9.

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1 solution

Chew-Seong Cheong
Jul 19, 2017

We note that x = 1 x=1 is a trivial real solution to the equation. The other real solution is given as follows:

x x 2 3 = x x x x 2 3 = x x 2 x 2 3 = x 2 x 1 2 3 = 2 x 1 3 = 2 x = 8 \large \begin{aligned} x^{\sqrt[3]{x^2}} & = \sqrt x^x \\ x^{x^\frac 23} & = x^{\frac x2} \\ \implies x^\frac 23 & = \frac x2 \\ x^{1-\frac 23} & = 2 \\ x^\frac 13 & = 2 \\ \implies x & = 8 \end{aligned}

Therefore, the sum of all real solutions is 1 + 8 = 9 1+8 = \boxed{9} .

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