Robuta

https://en.wikiversity.org/wiki/Ring/(x%5E2-3yzy-2zy%5E2%2B4xy%5E2)(2xy%5E3x-z%5E2xyx)(1-3zyxz%5E2y)/Compute/Exercise Ring/(x^2-3yzy-2zy^2+4xy^2)(2xy^3x-z^2xyx)(1-3zyxz^2y)/Compute/Exercise - Wikiversity