1. K = (a - 1)(a − 2)
=a*a +a*(-2) - 1*a -1*(-2) = a² - 2a - a + 2 = a² - 3a + 2
2. L = (2x - 5)(5x + 4)
= 2x*5x + 2x*4 - 5*5x - 5*4 = 10x² + 8x - 25x - 20 = 10x² - 17x + 4
3. M = (3x – 4)(1 - x)
=3x*1 + 3x*(-x) - 4*1 - 4*(-x) = 3x - 3x² - 4 + 4x = -3x² + 7x - 4
4. N = (-2y+3)(1 - y)
= -2y*1 - 2y*(-y) + 3*1 + 3*(-y) tu calcules et finis
5. O = (3x – 5)(2x - 8) – (7x + 2)(x+6)
= 3x*2x + 3x*(-8) - 5*2x - 5*(-8) - (7x*x + 7x*6 + 2*x + 2*6)
= 6x² - 24x - 10x + 40 - (7x² + 42x + 2x + 12)
tu peux finir
