Desperately need help!! Fan and medal! Calc III/Multivariable calculus problem: Construct a function whose level curves are lines passing through the origin. Please explain to me how you got to the answer, thank you.

Question

anonymous · Answer

How about planes that pass through the origin?

anonymous · Answer

Meaning, the function is a plane that passes through the origin

anonymous · Answer

I'm not sure if it'll satisfy what you want, since the question asks for a functions whose level CURVES (not singular) pass through (0,0,0)...