Explications étape par étape:
(x+1)(x-2)-x^2+3=0
x^2-2x+x-2-x^2+3=0
x^2-x^2-x+1=0
-x+1=0
-x=-1
x=1
3(2x^2+7)=(2x+1)(3x-5)
6x^2+21=6x^2-10x+3x-5
6x^2-6x^2+10x-3x+21+5=0
7x+26=0
7x=-26
x=-26/7
2(x-2)(x+3)+3(x^2-3)-5(x^2-4)=0
2(x^2+x-6)+3x^2-9-5x^2+20=0
2x^2+2x-12+3x^2-9-5x^2+20=0
5x^2-5x^2+2x-12-9+20=0
2x-1=0
2x=1
x=1/2
