Q1: How many different partial derivatives of order k are possible for a function f(x1,x2,....,xn) of n variables.

The answer is k-combinations of n+k-1.

Can anyone give an explanation in details?

Q2:The differential equation dp/dx=p(1-p)(p-2), possess the three equilibrium solutions p1=0, p2=1, p3=2, which of these are stable?

Also need an explanation in details........

Thanks for your replies.