Explications étape par étape:
(2x-3)(x+5) = (3-2x)(x+6)
(2x-3)(x+5) - (3-2x)(x+6)=0
(2x -3)(x+5)+(2x-3)(x+6)= 0
(2x-3)[(x+5)+(x+6])=0
(2x-3)[2x + 11] = 0
2x - 3=0 ou 2x + 11=0
x=3/2 ou x = -11/2
(6x-9)(11x+5) = (8x-12)(7x+6)
(6x-9)(11x+5) - (8x-12)(7x+6)=0
3 (2x-3)(11x + 5) - 4 (2x - 3)(7x +6)=0
(2x-3)[3 (11x+5) - 4 (7x+6)] =0
(2x-3)[33x+15 -28x -24)=0
(2x-3)(5x -9)=0
2x- 3=0 ou 5x-9=0
x=3/2 ou x=9/5
(14x-21)(2x+10) = 4x^2 +9 -12x
(14x-21)(2x+10) - ( 4x^2 -12x +9)=0
7(2x-3)(2x+10) - (2x-3)^2=0
(2x-3)[7 (2x+10) -(2x-3)]=0
(2x-3)[14x +70 -2x +3)=0
(2x -3)(12x+73)=0
2x -3=0 ou 12x+73=0
x=3/2 x= -73/12
18x^2 + 98 - 84x = 0
18x^2 -84x +98=0
2 (9x^2 - 42x +49)=0
9x^2 - 42x +49=0
(3x-7)^2=0
3x-7 =0
x= 7/3