Hello all,
I have this tricky question, I think I got the idea, just wish to confirm.
If the function
\[z=x\cdot ln(1+y)+a(x^{2}+y^{2})\]
has a local minimum at (0,0), then: (choose correct answer)
1) a<-0.5
2) a>0
3) a>0.5
4) -0.5<a<0.5
5) a>0.5 or a<-0.5
What I did, is calculate the...