Question

resolva as equações do segundo grau 2×(×+1)=×(×+5)+3 (12-×)

Answer 1

2x(x + 1) = x(x + 5) + 3
2x² + 2x = x² + 5x + 3
2x² - x² + 2x - 5x - 3 = 0
x² - 3x - 3 = 0

$\displaystyle \mathsf{\Delta = b^2 - 4.a.c}\\ \displaystyle \mathsf{\Delta = (-3)^2 - 4.(1).(-3)}\\ \displaystyle \mathsf{\Delta = 9 + 12}\\ \displaystyle \mathsf{\Delta = 21}$

$\displaystyle \mathsf{x = \frac{-b \: \pm \: \sqrt{\Delta}}{2a}}\\ \\ \displaystyle \mathsf{x = \frac{3 \: \pm \: \sqrt{21}}{2}}$

Resposta: $\displaystyle \mathsf{x = \frac{3 \: \pm \: \sqrt{21}}{2}}$