a) x = 0 8 - 2x ≥ 2 x => 8 ≥ 4 x => x ≤ 2
b) x + 7 = 0 soit x = -7 1 / x+7 > 3 => 1 > 3(x + 7) => 1 > 3x + 21 => 1 - 21 > 3x => - 20 > 3 x => x < - 20/3
c) x - 3 = 0 soit x=3 4 / x - 3 > 2/5 => 4 * 5 > 2(x - 3) => 20> 2x -6 => 20 + 6 > 2x => 26 > 2x => x < 26/2 => x< 13