Question

Add: 2x (z − x − y) and 2y (z − y − x)

Answer 1

First expression = 2x (z − x − y)

= 2xz − 2x² − 2xy

Second expression = 2y (z − y − x)

= 2yz − 2y² − 2xy

Adding the two expressions, we obtain.

−2x² − 2xy + 2xz
          −2xy          − 2y² + 2yz
_________________________
−2x² − 4xy + 2xz − 2y² + 2yz

Therefore, the sum of the given expressions is −2x² − 4xy + 2xz − 2y² + 2yz.