(x^2+4x-4)*(x^2+4x+1)=6 помогите решить уравснение срочно надо!!!! Методом введения новой...

(х^2 + 4х - 4)*(х^2 + 4х + 1) = 6
Замена: х^2 + 4х = y
(y - 4)*(y + 1) = 6
y^2 - 3y - 4 = 6
y^2 - 3y - 10 = 0
(y - 5)(y + 2) = 0
y1 = 5 ; y2 = -2

x^2 + 4x = 5 ; x^2 + 4x = -2
x^2 + 4x - 5 = 0 ; x^2 + 4x + 2 = 0
D = 4^2 - 4*1*(-5) = 36 = 6^2
D = 4^2 - 4*1*2 = 16 - 8 = 8.

x1 = 4 + 6 / 2 = 5
x2 = 4 - 6 / 2 = -1
x3 = 2 - v2
x4 = 2 + v2