Sagot :
A = (x+3)(a+5)
A = xa +5x +3a +15
B= (a +6)(5+b)
B = 5a +ab +30 +6b
C = (x+2)(y-1)
C= xy -x +2y -2
D = (a-2)(b+4)
D = ab +4a -2b -8
Bonsoir,
On applique la formule :
[tex]\left(a+b\right)\left(c+d\right) = ac+ad+bc+bd[/tex]
a)[tex]\left(x+3\right)\left(a+5\right)\\ =ax+5x+3a+3\times 5\\ =ax+5x+3a+15\\[/tex]
b)[tex]\left(a+6\right)\left(5+b\right)\\ =5a+ab+6\times 5+6b\\ =5a+ab+6b+30[/tex]
c)[tex]\left(x+2\right)\left(y-1\right)\\ =xy-x+2y-2[/tex]
d)[tex]\left(a-2\right)\left(b+4\right) = ab+4a-2b-8[/tex]