Respuesta :
4x^2 + 12 x +9 =81
4x^2 + 12x -72 = 0
x^2 + 3x -18 = 0
-3±√(3²+4 . 18
x = -----------------
2
x1 = 3
x2 = -6
4x^2 + 12x -72 = 0
x^2 + 3x -18 = 0
-3±√(3²+4 . 18
x = -----------------
2
x1 = 3
x2 = -6