Question

Resolva a esquação
- x elevado ao quadrado +2x +8 =0

Me ajuda

Answer 1

Δ = D

$- x^{2} + 2x +8\\\\ D = b^{2} - 4ac\\ D = (2)^2- 4 * (-1) * 8\\ D = 4 + 32\\ D = 36$


$x = \frac{-b_-^+ \sqrt{D} }{2a} \\\\ x^, = \frac{-(2) + 6 }{2 * (-1)}\\\\ x^, = \frac{-2 + 6 }{-2}\\\\ x^, = \frac{4 }{-2}\\\\ x^, = -2$


$x^{,,} = \frac{-(2) - 6 }{2 * (-1)}\\\\ x^{,,} = \frac{-2 - 6 }{-2}\\\\ x^{,,} = \frac{-8}{-2}\\\\ x^{,,} = 4$