Hi,

Solve for x:

$\displaystyle (a.)\,4^x - 13(2^x) + 40 = 0$

This is supposed to have two solutions (quadratic), but I've only progressed two steps. I believe these two steps to be incorrect. Argh!

$\displaystyle 4^x - 26^x + 40 = 0$

$\displaystyle -22^x + 40 = 0$