bonsoir
A= (7x-8)*-(2x+5)*
49x² -112x +64 -(4x²+20x+25)
49x²-112x+64-4x²-20x-25
45x²-132x+39
B= (6y-1)(6y+1)+(4y-3)(3y-4)
= 36y²-1 +12y²-16y-9y+12
= 48y²-25y+11
b) Factoriser
D= (6a+7)*-(6a+7)(2a+3)
(6a+7)(6a+7-2a-3)
(6a+7)(4a+4)
Puis résoudre l'équation D = 0
(6a+7)(4a+4) =0
6a+7 =0 4a+4 =0
6a = -7 4a = -4
a = -7/6 a = -4/4 = -1