{x + y + z + w - 2 = 0, y^2 - (x*(x + 1)) = 0, z^2 - (x*(x + 2)) = 0, w^2 - ((x + 1)*(x + 2)) = 0};

{x + y + z + w - 2 = 0, y^2 - (x*(x + 1)) = 0, z^2 - (x*(x + 2)) = 0, w^2 - *1 = 0};
      KARA  {y,z,w} を消去してください;
 https://www.youtube.com/watch?v=pHtDaScwNjU　
 　

*1:x + 1)*(x + 2