Bonjour,
2(4x - 5) = 4 + x
2 * 4x + 2 * -5 = 4 + x
8x - 10 = 4 + x
8x - x = 4 + 10
7x = 14
x = 14/7 = 2
2(x + 8) + 3 = 4 - 3x
2 * x + 2 * 8 + 3 = 4 - 3x
2x + 16 + 3 = 4 - 3x
2x + 19 = 4 - 3x
2x + 3x = 4 - 19
5x = -15
x = -15/5 = -3
12x - 1 = 2(5x - 2) + 1
12x - 1 = 2 * 5x + 2 * - 2 + 1
12x - 1 = 10x - 4 + 1
12x - 10x = -4 + 1 + 1
2x = -2
x = -2/2 = -1
(x - 3)² = x(x - 5)
x * x + x * - 3 * 2 + (-3)² = x * x + x * -5
x² - 6x + 9 = x² - 5x
x² - x² - 6x + 5x = -9
-x = -9
x = 9
Il a raison