Réponse :
A = (2/5x - 2/3)² - (3/5x - 2/3)² = (2/5x) - 2/3)(2/5x - 2/3) - (3/5x - 2/3)(3/5x - 2/3) = (4/25x² - 4/15x - 4/15x + 4/9) - (9/25x² - 6/15x - 6/15x + 4/9)
A = 4/25x² - 8/15x + 4/9 - 9/25x² + 12/15x - 4/9
A = - 5/25x² + 4/15x = -1/5x² + 4/15x
B = (7x - 4/3)(7x + 4/3) - (7x + 4/3)² = (49x² + 28/3x - 28/3x - 16/9) - (7x + 4/3)(7x + 4/3) = 49x² - 16/6x - (49x² + 28/3x + 28/3x + 16/9)
B = -16/6x - 56/3x - 16/9 = (-8/3x - 56/3x=-64/3x) - 16/9
C = (x² - 1)² - (x² + 1)²
C = (x² - 1)(x² - 1) - (x² + 1)(x² + 1)
C = x^4 - x² - x² + 1 - x^4 - x² - x² - 1
C = -4x²
D = (a² - b + 1)(a² + b - 1) + (b - 1)²
D = a^4 + a²b - a² - a²b - b² + b + a² + b - 1 + (b - 1)(b - 1)
D = a^4 + - b² + 2b - 1 + b² - b + b + 1
D = a^4 + 2b
Explications étape par étape
