Réponse:
12x -4 = 20x +28
12 -20x = 28 +4
-8x = 32
-8x/-8 = 32/-8
x = -4
(3x -4×2x +5) = 0
(3x -8x +5) = 0
-5x +5 = 0
-5x = -5
-5x/-5 = -5/-5
x = 1
2(3x-4) - (2x+5) = 0
6x -8 -2x -5 = 0
6x -2x = 8 +5
4x = 13
4x/4 = 13/4
x = 13/4
(5x-7)2 = 0
10x -14 = 0
10x = 14
10x/10 = 14/10
x = 14/10
x = 7/5
2x +20x +100 = 0
22x = -100
22x/22 = -100/22
x = -100/22
x= -50/11