Odpowiedzi

2010-01-16T13:08:26+01:00
Df/dx=[1*xy-y(x+y)]/x²y²=[xy-xy-y²]/x²y²=-y²/x²y²=-1/x²

df/dy=[1*xy-x(x+y)]/x²y²=[xy-x²-xy]/x²y²=-x²/x²y²=-1/y²