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)

Bonjour,

A= a^2+5a+7a+35 =a^2+12a+35

B=x^2+5x-4x-20 = x^2+x-20

C=9x+27-x^2-3x = -x^2+6x+27

D = (-x-1)(5-x)
D=-5x + x^2-5+x = x^2-4x-5

Bonjour, 
A = (a + 7)(a + 5)
A= a² + 5a + 7a + 35
A = a² + 12a + 35 

B = (x - 4)(x + 5)
B = x² + 5x - 4x - 20
B = x² + x - 20 

C = (x + 3)(9 - x)
C = 9x + 27 - x² - 3x
C = - x² + 6x + 27 

D = ( - x - 1)(5 - x)
D = - 5x + x² - 5 + x
D = x² - 4x - 5