Bonjour
5x * 3x = 15x^2
-6x^2 + 4x + 2x + 7x^2 - x^2 = 7x^2 - 6x^2 - x^2 + 4x + 2x = 6x
x + x = 2x
(-2x)(-4x) = 8x^2
(3x + 2) - (3x + 9) = 3x + 2 - 3x - 9 = -7
x * 6x = 6x^2
3 - 5x => inchangé
x * x = x^2
2x * 4 = 8x
x^2 + 7x - 7(x^2 + x) = x^2 + 7x - 7x^2 - 7x = x^2 - 7x^2 + 7x - 7x = -6x^2
2x(2x + 1) = 2x * 2x + 2x * 1 = 4x^2 + 2x
5x - (2x - 5) = 5x - 2x + 5 = 3x + 5