Sagot :
A = 5x*2x-5x*3 -(3x*2x+3x*4)
=10x²-15x-6x²-12x=4x²-27x
B=7x*3x+7x*5-2*3x-2*5=21x²+35x-6x-10=21x²+29x-10
C=3x*3x-3x*8-4*3x+4*8=9x²-24x+12x+32
=9x²+12x+32
Explications étape par étape:
A=5×(2x-3) - 3×(2x+4)
=10x - 15 - 6x + 12
=4x - 3
B=(7x-2)(3x-5)
=21x^(2) + 35x - 6x -10
= 21x^(2) + 29x - 10
C=(3x-4) (3x-8)
=9x^(2) - 24x -12x + 32
=9x^(2) - 36x + 32