Bonjour,
.c=(x-7) ( x+9 )
= x² +9x-7x -63
= x² +2x -63
.d = ( x-3 ) ( 4-x )
= 4x -x² -12 +3x
= -x² +7x -12
.E= ( 3x+4 ) (5 x -7 )
= 15x² -21x +20x -28
= 15x² -x -28
.F = ( -2x +8 ) ( 4 - x )
= -8x +2x² +32 -8x
= 2x² +32
Explications étape par étape:
C=(x-7)(x+9)
C=x2+9x-7x-63
C=x2+2x-63
D=(x-3)(4-x)
D=4x-x2-12+3x
D= -x2+7x-12
E=(3x+4)(5x-7)
E=15x2-21x+20x-28
E=15x2-x-28
F=(-2x+8)(4-x)
F= -8x +2x2+32-8x
F= -16x +2x2+32