b: \(=\left(b-c+c-a\right)^3-3\left(b-c\right)\left(c-a\right)\left(b-c+c-a\right)-\left(b-a\right)^3\)
\(=-3\left(b-c\right)\left(c-a\right)\left(b-a\right)\)
c: \(=\left(x^2+y^2+z^2-x^2\right)^3-3\left(x^2+y^2\right)\left(z^2-x^2\right)\left(x^2+y^2+z^2-x^2\right)-\left(y^2+z^2\right)^3\)
\(=-3\left(x^2+y^2\right)\left(z^2-x^2\right)\left(y^2+z^2\right)\)