Bonsoir
(-3+2x)(5x-2) = -15x+6+10x²-4x = 10x²-19x+6
3(5x-2) = 15x-6
(5x-2)(5x+2) = 25x²- 4 ( identité remarquable (a-b)(a+b)=a²-b²
donc
(-3+2x)(5x+2)+(25x²-4)+3(5x-2)
= (-3+2x)(5x-2)+(5x-2)(5x+2)+3(5x-2) on prend (5x-2) comme facteur commun
= (5x-2)(-3+2x+5x+2+3)
= (5x-2)(7x+2)
