Question 990572
{{{ (3z-x)(z^3-3z^2x+2zx^2-x^3) =(3z^4-9z^3x+6z^2x^2-3zx^3)-(xz^3-3z^2x^2+2zx^3-x^4)}}}
{{{(3z-x)(z^3-3z^2x+2zx^2-x^3)=3z^4-10z^3x+9z^2x^2-5zx^3+x^4}}}