Bonsoir,
A = (2x -1)² - (5x + 1)(6x - 3) + (8x² - 2)
A = (2x - 1)(2x - 1) - 3(5x + 1)(2x - 1) + 2(4x² - 1)
A = (2x - 1)(2x - 1) - 3(5x + 1)(2x - 1) + 2(2x + 1)(2x - 1)
A = (2x - 1)[2x - 1 - 3(5x + 1) + 2(2x +1)]
A = (2x - 1)(2x - 1 - 15x - 3 + 4x + 2)
A = (2x - 1)(-9x - 2)
développement :
A = (2x -1)² - (5x + 1)(6x - 3) + (8x² - 2)
A = 4x² - 4x + 1 - 30x² + 9x + 3 + 8x² - 2
A = 4x² - 30x² + 8x² - 4x + 9x + 1 + 3 - 2
A = -18x² + 5x + 2
