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answer is sqrt(10)*4.. don't know why

yeah sorry should have said z=3sqrt(x^2+y^2)..

Homework Statement Find the surface area of the cone z=3x^2+y^2and above a region in the xy-plane with area 4. Homework Equations double integral sqrt( (dz/dx)^2 + (dz/dy)^2 +1) The Attempt at a Solution I was able to simplify the equation, I just don't know what to do...

yeah, I am sure.. but to get it right they all have to be right.. I am pretty confident about the last two limits.. its mainly the first two that are bugging me

I understand what you mean but, for example, if I take the fourth limit: lim(x,y)->(0,0) (x^2 * y^2) / (x^4 + 5y^4) If I evaluate this when x=y then I end up with (x^4)/(6x^4) which gives a limit of 1/6. However, if I evaluate this at (x,0) which should also work, I get a limit of 0/(x^4) =...

I can't get this problem right and it's part of a web-based assignment that I have to submit. In order to get credit for the problem, all of my answers need to be right; I've tried many different times and I can't seem to figure out what I am doing wrong. Here it is with my explanations as to...