Réponse :

bonjour

A = ( a + 1 ) ² = a² + 2 a + 1

B = ( 5 x + 2 )² = 25 x² + 20 x + 4

C =  ( 3 y - 4 )² = 9 y² - 24 y + 16

D = ( 4 - x )² = 16 - 8 x + x²

Explications étape par étape :

Réponse:

20)

(x+4)(x+3)=x2+3x+4x+12=x2+7x+12

(y+3)(2y+8)=2y2+8y+6y+24=2y2+14y+24

(3z+4)(5-6z)=15z-18z2+20-24z=18z2-9z+20

(5z-7)(8z+2)=40z2+10z-56z+14=49z2-46z+14

22)

A=(a+2)2=a2+4a+4

B=(5x +2)2=25x2+20x+4

C=-(y+5)(3y-6)

C=-(3y2-6y+15y-30)=-3y2-9y+30

D=x(2x-5)(2-x)=x(4x-2x2-10+5x)=x(-2x2+9x-10)=-2x3+9x2-10x

21)

(7-3x)(9x-3)=63x-21-27x+9x=55x-21

(_2-3y)(4-8y)=-8+16y-12y+24y2=24y2+4y-8

(4a+6)(-3-5a)=-12a-20a2-18-30a=-20a2-42a-18

(5z-7)(8z+2)=40z2+10z-56z-14=40z2-46z-14