Solution
= Solution
The solution set is the <plane> through the origin with <normal vector> $(1,1,1)^T$. The three original <planes> coincide, so their common intersection is this entire <plane>.
= Solution
The solution set is the <plane> through the origin with <normal vector> $(1,1,1)^T$. The three original <planes> coincide, so their common intersection is this entire <plane>.