Hi, i have two problems that i really need help with. The problems are due tomorrow at 2:30. can someone please help me out, i'll really appreciate it.

implicit differentiation problem

1) (x^2+y^2)/(x+y)=xy-2

find derivitive (dy/dx) at point (-1, -1)

maxima/minima problem

2)a cylinder, including top and bottom, is madde from material which costs "x" dollars per square inch. Suppose their is an additional cost of fabrication given by "n" dollars per inch of the circumfrence of the top and bottom of the can. find an algerbraic equation whose solution would be he radius , r, of the can of given volume, V, whose cost is a minimum.

* Do not have to solve equation, just find a algerbraic solution

Thank you in advance.