=a^2b-a^2c-b^2a+b^2c+c^2a-c^2b
=b(a^2-c^2)-a^2c+c^2a-b^2(a-c)
\(=\left(a-c\right)\left[b\left(a+c\right)-ac-b^2\right]\)
\(=\left(a-c\right)\left(ab+bc-ac-b^2\right)\)
\(=\left(a-c\right)\left[a\left(b-c\right)+b\left(c-b\right)\right]\)
\(=\left(a-c\right)\left(b-c\right)\left(a-b\right)\)