Développer chaque expression. A: ( x + 2) ( y + 3) = B : ( a + 5 ) ( 7 + b ) = C : ( 4a + 2 ) ( 1 + 5b ) = D : ( 6y + 1 ) ( 9 + x ) =

A = ( x +2 ) ( y + 3 ) = x*y + x*3 + 2*y + 2*3 = xy + 3x + 2y + 6.

B= ( a + 5 ) (7+ b ) = a*7 + 1*b + 5*7 + 5*b = 7a+ b + 35 + 5b = 7a + 6b + 35.

C = ( 4a + 2 ) ( 1 + 5b ) = 4a * 1 + 4a* 5b + 2*1 + 2*5b = 4a + 4a5b + 2 - 10b.

A: ( x + 2) ( y + 3)
= xy + 3x + 2y + 6

B : ( a + 5 ) ( 7 + b )
= 7a + ab + 35 + 5b

C : ( 4a + 2 ) ( 1 + 5b ) 
= 4a + 20ab + 2 + 10b

D : ( 6y + 1 ) ( 9 + x )
= 54y + 6xy + 9 + x