Bonjour !
a.
(5x + 7)(x - 3) - (x - 3)(x + 2)
= (x - 3) [(5x + 7) - (x + 2)]
= (x - 3)(5x + 7 - x - 2)
= (x - 3)(4x + 5)
b.
(x - 3)(2x - 5) + 2x - 6
= (x - 3)(2x - 5) + 2(x - 3)
= (x - 3) [(2x - 5) + 2]
= (x - 3)(2x - 5 + 2)
= (x - 3)(2x - 3)
c.
(x - 3)² + x - 3
= (x - 3)(x - 3) + 1(x - 3)
= (x - 3) [(x - 3) + 1]
= (x - 3)(x - 3 + 1)
= (x - 3)(x - 2)
d.
(x + 3)(x - 3) - 5(x - 3)²
= (x + 3)(x - 3) - 5(x - 3)(x - 3)
= (x - 3)[(x + 3) - 5(x - 3)]
= (x - 3)(x + 3 - 5x + 15)
= (x - 3)(-4x + 18)
= 2(x - 3)(-2x + 9)
J'espère t'avoir aidé. Bon courage !
