Sagot :
Factoriser: (5x+1)²-(3x+4)² = (2x-3)(8x+5) OK.
Factoriser: (2x+5)(2x-3)+(x-2)(2x-3)+4x²-9 = (2x-3)(6x-6) ?
La réponse : (2x+3)(5x+6)
Developper: ( 2x+5)(2x-3)+(x-2)(2x-3)+4x²-9=4x²-6x+10x-15+2x²-3x-4x+6+4x²-9=10x²-3x-18
Developper: (5x+1)²-(3x+4)²=25x²+10x+1-9x²-24x-16=16x²-14x-15
Developper: (4x-6)(x-3)-(2x-3)²-10x²+15x=4x²-12x-6x+18-(4x²-12x+9)-10x²+15x=-10x²+9x+9
Factoriser: (4x-6)(x-3)-(2x-3)²-10x²+15x=2(2x-3)(x-3)-(2x-3)²-5x(2x-3)=
=(2x-3)(2x-6-2x+3-5x)=(2x-3)(-3-5x)