1) 5x - (x + 3 ) = 3 ( x - 2 )
5x - ( x + 3 ) = 3x - 6
5x - x + 3 - 3x + 6 = 0
x + 9 = 0
x = - 9
2) - (-2x + 8) - 5x (3x + 4) = -5 ( 3x^2 - 2)
2x - 8 - 15x^2 - 20x = -15x^2 + 10
2x - 8 - 15x^2 - 20x + 15x^2 - 10 = 0
2x - 8 20x -10 = 0
-18x -18 = 0
x = 1
3) x/2 - 5 = -7/2 + 2x
x/2 - 5 + 7/2 - 2x = 0
x/2 - 4x/2 - 5 + 7/2 = 0
x - 4x /2 - 10/2 + 7/2 = 0
-3x/2 - 17/2 = 0
-3x - 17 = 0
x = -17/3
4) x^2 - 21 = 4
x^2 - 21 - 4 = 0
x^2 - 25 = 0
supposant x^2 = 2x
alrs on a : 2x = 25
x = 25/2
x = 12.5
5) ( 3x + 2 )^2 - 16 = 0
9x^2 + 12x + 4 - 16 = 0
9x^2 + 12x - 12 = 0
si x^2 = 2x alrs on a : 9*2x + 12x - 12 = 0
18x + 12x - 12 = 0
30x - 12 = 0
30x = 12
x = 2/5
