If 9x+2y^2−3z^2=132 and 9y−2y^2+3z^2=867, then x+y =

Step-by-step explanation:

Step 1: Identify the approach:

With this problem, the general solution is to try manipulate given data and transform data into a new form, in which, the desired value is on the left side and all of other components which do not contain or are on the right side.

Step 2: Analyze:

Realize that in both equations, the and are in form of different signs. Then adding up corresponding sides of both equation can help eliminate these undesired components.

Step 3: Perform manipulation:

Rearrange:

Simplify:

Simplify:

Hope this helps!

:)