Bonjour,
Développer:
F) ( 2x +3)²= ( 2x +3)( 2x +3)= 4x²+6x+6x+9= 4x²+12x+9
G) ( 4- 7x) (4 + 7x)= 16-28x+28x-49x²= -49x²+16
H) ( x + 4) (x-6)+( -1 + x)( x-7)= x²+4x-6x-24-x+x²+7-7x= 2x²-10x-17
I) -3(a²+2) -(a-3) (2a +7)= -3a²-6-(2a²-6a+7a-21)= -3a²-6-(2a²+a-21)
= -3a²-6-2a²-a+21= - 5a²-a+15
J) 4- (2x +1)²= 4-(4x²+2x+2x+1)= 4 -(4x²+4x+1)= 4-4x²-4x-1= - 4x²-4x+3
