Bonsoir,
3)
4 (x-3)(x+2) - (x²-9) = 0
⇔ 4 (x-3)(x+2) - (x-3)(x+3) = 0
⇔ (x-3)(4x+8) - (x-3)(x+3) = 0
⇔ (x-3)(4x+8-x-3) = 0
⇔ (x-3)(3x+5) = 0
⇔ x=3 ou x = -5/3
S3 = {-5/3 ; 3}
4) on note d'abord que x ≠ -2
(2x-1)/(x+2) = 5
⇔ 2x - 1 = 5x + 10
⇔ 3x = -11
⇔ x = -11/3
S4 = {-11/3}
