Réponse :
bonjour
Explications étape par étape :
exercice 1:
(2x – 5)(7 + 4x) = 14x+8x-35-20x= 42x-35
(3x – 5)²= 9x²-30x+25
5x(2x + 4) + (5x – 2)(5x + 2)= 10x²+20x+25x²+10x-10x-4= 35x²+20x-4
exercice 2:
12x(4x + 7) + 7(4x + 7)
= (4x+7)(12x+7)
(2x – 5)(7 + 8x) – (4 + 5x)(2x – 5)
= (2x-5)(7+8x-4+5x)=(2x-5)(3+13x)
exercice 3:
E = (7 – 5x)² – (7 + 5x)(7 – 5x)
a) 49+70x-25x²-(49-35x+35x-25x²)
= 49+70x-25x²-49+35x-35x+25x²
= 70x
b) (7 – 5x)² – (7 + 5x)(7 – 5x)
= (7-5x)(7-5x-7-5x)= (7-5x)(-10x)
c) E = (7 – 5x)² – (7 + 5x)(7 – 5x)
x=0
e= (7)²-(7)(7)= 49-49=0
je te laisse les autres exercices ;)
