Question

despejar x en :

x² + 8x -9 = 0 ( PROCESO )

Answer 1

x² + 8x -9= 0

x = {-8±√(8²-(4*1*-9))} / (2*1)
x = {-8±√(64+36)} / 2
x = {-8±√100} / 2
x = {-8±10} / 2
x₁ = {-8-10} / 2 = -18/2 = -9
x₂ = {-8+10} / 2 = 2/2 = 1

Comprobación:
9² + (8*-9) - 9 = 0
81 -72 - 9 = 0

1² - (8-1) - 9 = 0
1 + 8 - 9 = 0

Respuesta:
Hay dos soluciones:
x₁ = -9
x₂ = 1