Bonjour,
Factoriser:
A=2x-3+(3-2x)(x+5)= (2x-3) - (2x-3)(x+5)= (2x-3)(1-x-5)= (2x-3)(-x-4)
= - (2x-3)(x+4)
B=(x - 5)(2x + 3) - x² +25= (x-5)(2x+3)-(x²-25)= (x-5)(2x+3)-(x-5)(x+5)
= (x-5)(2x+3-x-5)= (x-5)(x-2)
C=(6x-10)(4-x) - (5-3x)²= 2(3x-5)(4-x) +(3x-5)(5-3x)= (3x-5)(2(4-x)+5-3x)
= (3x-5)(8-2x+5-3x)= (3x-5)(-5x+13)= - (3x-5)(5x-13)