Bonjour,
Factoriser:
f(x)=x²-9-(x+3)(7x-14)-2(x+3)
= (x-3)(x+3)-(x+3)(7x-14)-2(x+3)
= (x+3)(x-3-7x+14-2)
= (x+3)(-6x+2)
= - 3(x+3)(2x-3)
g(x)= (3-2x)²+(2x-3)(1-2x)
= (3-2x)(3-2x)+(-3+2x)(1-2x)
= (3-2x)(3-2x)-(3-2x)(1-2x)
= (3-2x)(3-2x-1+2x)
= (3-2x)(2)
= -2(2x-3)
