D=(2x-3)²+(2x-3)(x-2)
=(2x-3)(2x-3+x-2)
=(2x-3)(3x-5)
=6x²-19x+15
E=25-(2x-1)²
=(5-2x+1)(5+2x-1)
=(-2x+6)(2x+4)
=-4x²+4x+24
F=4x²-9-(2x+3)(x-2)
=(2x-3)(2x+3)-(2x+3)(x-2)
=(2x+3)(2x-3-x+2)
=(2x+3)(x-1)
D=0 donne x=3/2 ou x=5/3
E=0 donne x=3 ou x=-2
F=0 donne x=-3/2 ou x=1
