developer puis reduire les expressions
A = (a+7)(a+5)
B = (x-4)(x+5)
C = (+x+3)(9-x)
D = (-x-1)(5-x)
A = (a+7)(a+5)
B = (x-4)(x+5)
C = (+x+3)(9-x)
D = (-x-1)(5-x)