Developper et reduire A= (7t+3)(t-4) - (t-2)(t+6) B= 2x (8x-1) - (4x-5)(4x-1)

A= (7t+3)(t-4)-(t-2)(t+6)
A=7t²-28t+3t-12-t²-6t+2t+12
A=6t² -21t 

B= 2x(8x-1)-(4x-5)(4x-1)
B=16x²-2x-16x²+4x+20x-5
B=22x-5

A = (7t + 3) (t - 4) - (t - 2) (t + 6)
A = 7t * t + 7t * (- 4) + 3 * t + 3 * (- 4) - (t * t + t * 6 - 2 * t - 2 * 6)
A = 7t² - 28t + 3t - 12 - (t² + 6t - 2t - 12)
A = 7t² - 28t + 3t - 12 - t² - 6t + 2t + 12
A = 6t² - 29t

B = 2x (8x - 1) - (4x - 5) (4x - 1)
B = 2x * 8x + 2x * (- 1) - [4x * 4x + 4x * (- 1) - 5 * 4x - 5 * (- 1)]
B = 16x² - 2x - (16x² - 4x - 20x + 5)
B = 16x² - 2x - 16x² + 4x + 20x - 5
B = 22x - 5

Les * désignent "fois".