Question

2×(×+1)-×(×+5)=3 (12-×)​

Answer 1

Resposta:

$\sf 2x \cdot (x + 1) - x \cdot (x+5) = 3 (12- x)$

$\sf 2x^{2} +2x - x^{2} - 5x = 36 -3x$

$\sf 2x^{2} - x^{2} + 2x +3x- 5x - 36 = 0$

$\sf x^{2} + 5x - 5x - 36 = 0$

$\sf x^{2} - 36 = 0$   ←  equação do 2° incompleta com b = 0.

$\sf x^{2} = 36$

$\sf x = \pm \: \sqrt{36}$

$\sf x = \pm \: 6$

$\boldsymbol{ \sf \displaystyle x_1 = -\:6 }$

$\boldsymbol{ \sf \displaystyle x_2 = 6 }$

$\sf \boldsymbol{ \sf \displaystyle S = \{ x \in \mathbb{R} \mid x = -\: 6 \mbox{\sf \;e } x = 6 \} }$