$(x - 2)(x^2 + 2x + 4) = x^3 + 24x$
$x^3 - 8 = x^3 + 24x$
$24x + x^3 - x^3 = -8$
$x = -\frac{8}{24} = -\frac{1}{3}$

$(3 - 2x)(9 + 6x + 4x^2) - 2x(5 - 2x)(5 + 2x) = 7$
$27 - 8x^3 - 2x(25 - 4x^2) = 7$
$27 - 8x^3 - 50x + 8x^3 = 7$
−50x = 7 − 27
$x = \frac{20}{50} = \frac{2}{5}$