b: \(=xy\left(x+1\right)+\left(x+1\right)=\left(x+1\right)\left(xy+1\right)\)
c: \(=x^2-ax-bx+ab\)
\(=x\left(x-a\right)-b\left(x-a\right)\)
\(=\left(x-a\right)\left(x-b\right)\)
e: \(=a\left(x^2+y\right)-b\left(x^2+y\right)\)
\(=\left(x^2+y\right)\left(a-b\right)\)