a) \(ax+ay+bx+by=a\left(x+y\right)+b\left(x+y\right)=\left(a+b\right)\left(x+y\right)\)
\(=-2.17=-34\)
b) Ta có: \(x-y=-1\Rightarrow x=-1+y\)
\(ax+ay+bx+by=a\left(x+y\right)+b\left(x+y\right)=\left(a+b\right)\left(x+y\right)\)
\(=-7.\left(-1+y+y\right)\)
\(=7-14y\)
a) ax + ay + bx + by
= a(x + y) + b(x + y)
= (a + b)(x + y)
= (-2) + 17
= 15