If we want to solve for x given:

(5x + 4)2 - 2 = 7

Then is it best to expand first? When I do this I get: 25x2+ 40x + 7=0

Should I factor after this?

Thanks

$(5x+4)^2 = 9$
$|5x+4| = 3$
$5x +4 = 3 \implies x = -\dfrac{1}{5}$
$5x+4 = -3 \implies x = -\dfrac{7}{5}$