so your equation would be (x)squared + 3(x+2) = 24
simplify:
xsq + 3x + 6 = 24
xsq + 3x - 18 = 0
if we broke this down into multiplication, one of the multiplying factors would have to equal zero since the whole now equals 0 so,
(x+6)(x-3) = 0
so, x+6 = 0, or x-3 = 0
solve:
x = -6, or 3
then just choose the odd one