1) (2x-3)(5-x)+(2x-3)² =(10x-2x²-15+3x) +(4x²-12x+9)= 2x²+x-6= 2(x²+x/2-3)
2) (2x-3)[(5-x)+(2x-3)]=(2x-3)(2+x)
3) pour x=-3 alors (2*-3-3)(2+-3)=(-6-3)(-1)= 9 donc D={9}
4) (2x-3)(2+x)=0 càd 2x-3=0 et 2+x=0 soit x=3/2 et x=-2
A=3/4 + 1/2*(2/3-1) = 3/4 + (1/3-1/2) = 3/4+( 2/6-3/6) =3/4-1/6 = 9/12-2/12=7/12
B= 2√63-√112+3√28= 3√28-4√28 +3√28 = - 4√28
C= 5*36/15 * 10^-9 = 12*10^-9
4x²=16 donc x²=4 x=2
2x-1=7x+8 donc -5x = 9 x=-9/5
1/3x+5=-7/6x-5/12 donc 1/3x + 7/6x = -5-5/12 9/6x = 55/12 x = 55*6 / 9*12
x=55/18
