Functions, graphs and inverses practice question 9

Look at the two powers of 2 in the equation. How is $2^{2x}$ related to $2^{x}$?

$2^{2x} = \bigl(2^{x}\bigr)^{2}$. The equation is a quadratic in disguise.

Let $u = 2^{x}$. Solve $u^{2} - 6u + 8 = 0$, then convert each $u$ back to an $x$.