Bonsoir,
1) (3x+2)²-(5-2x)(3x+2) = 9x²+12x+4-(15x+10-6x²-4x)
= 9x²+6x²+12x-15x+4x+4-10
= 15x²+x-6
2) (3x+2)²-(5-2x)(3x+2) = (3x+2)(3x+2)-(5-2x)(3x+2)
= (3x+2)[(3x+2)-(5-2x)]
= (3x+2)(5x-3)
3) si x = -2
E = (3(-2)+2)(5(-2)-3) = (-4)(-13) = 52