a, \(ax^2+ay^2-bx^2-by^2+b-a\)
\(=a\left(x^2+y^2\right)-b\left(x^2-y^2\right)-\left(a-b\right)\)
\(=\left(a-b\right)\left(x^2+y^2\right)-\left(a-b\right)\)
\(=\left(a-b\right)\left(x^2+y^2-1\right)\)
b, \(ac^2-ad-bc^2+cd+bd-c^3\)
\(=a\left(c^2-d\right)-\left(bc^2-bd\right)-\left(c^3-cd\right)\)
\(=a\left(c^2-d\right)-b\left(c^2-d\right)-c\left(c^2-d\right)\)
\(=\left(a-b-c\right)\left(c^2-d\right)\)