Bonjour,
50 - (x + 20) = 50 - x - 20 = 30 - x
-(10 + x) + (x + 5) = -10 - x + x + 5 = -5
(x² - 4x) - (5x² + 2x - 1) = x² - 4x - 5x² - 2x + 1 = -4x² - 6x + 1
-(3 - x + x²) + (-2x + 3x² - 8) = -3 + x - x² - 2x + 3x² - 8 = 2x² - x - 11
x - 4 - (2 + x) + (x + 5) = x - 4 - 2 - x + x + 5 = x - 1
-(x - 8) + (x - 6) - (7 - x) = -x + 8 + x - 6 - 7 + x = x - 5
(x² + 5x - 4) - (-2x² + 9x - 7) = x² + 5x - 4 + 2x² - 9x + 7 = 3x² - 4x + 3
