Bonsoir,

a)

2x+2x = 8

4x= 8

x = 8/4

x= 2

b)

-8 -4 = 7x -4x

-12 = 3x

x = -12/3

x= -4

c)

5+9 = 6x -3x

14 = 3x

x = 14/3

x

x-10

(x-10) ² =  x² -20x +100

x² -20x +100 -x² = -20x  + 100

-20x+100 = -340

-20x = -340 -100

-20x = -440

x = -440/-20

x =22

je pense à 22