Question

Solve the equation below:

Answer 1

$\sqrt[3]{x^2-8}=2 \\ x^2-8=2^3=8 \\ x^2=16 \\ \\ \boxed{x=4 \ or \ -4}$

Answer 2

Both x=4 and x=-4 satisfy the given equation.  So, the correct answer is (c).