Bonsoir
1)(3x+1)²-(3x+1)(2x-1)
9x²+6x+1-(6x²-3x+2x-1)
9x²+6x+1-6x²+3x-2x+1
3x²+7x+2
2)(3x+1)²-(3x+1)(2x-1)
(3x+1)(3x+1-2x+1)
(3x+1)(x+2)
3a)(3x+1)(x+2)=0
3x+1=0 ou x+2=0
x=-1/3 ou x=-2
b)x=2/3
=3*(2/3)²+7*2/3+2
=3*4/9+7*2/3+2
=4/3+14/3+2
=4/3+20/3
=8
*=multiplier
