(x-2)²+7x-4=(x-1)(x+2)
on remplace x par 2(x-2)²+7x+4 = (2-2)²+14-4 = 10
(x-1)(x+2) =(2-1)(2+2) = 1*4 = 4
2 n'est pas solution
2) x²-4x+4+7x-4 = x²+3x
3) (x-1)(x+2) = x²+2x-x-2 = x²+x-2
4) on sait que (x-2)²+7x-4 = x²+3x et (x-1)(x+2) = x²+x-2
x²+3x = x²+x-2
x²+3x-x²-x = -2
2x = -2
5) 2x =-2
x = -2/2 = -1