Question

2x (x+1) -3 (12-x) = x (x+5)

Answer 1

$2x (x+1) -3 (12-x) = x (x+5) \\ \\ 2 x^{2} +2x + 3x - 36 = x^{2} +5x \\ \\ 2 x^{2} + 2x + 3x - 36 - x^{2} - 5x \\ \\ \\ x^{2} - 36 = 0$

Resolvendo por Bháskara:


$x = \frac{-b \pm \sqrt{b^2 -4*a*c}}{2*a}$

$x^{2} - 36 = 0$

$x = \frac{-0 \pm \sqrt{144}}{2*1} \\ \\ x = \frac{0 \pm 12}{2} \\ \\ x' = \frac{0 + 12}{2} \\ \\ x' = \frac{12}{2} \\ \\ x' = 6 \\ \\ \\ x'' = \frac{0 - 12}{2} \\ \\ x'' = \frac{-12}{2} \\ \\ x'' = -6$

S = {6, -6}