I need to find the partial derivative of m with respect to v with m equal to the following:

m sub o / (1 - v^2/c^2)^(1/2)

The answer is listed in the book but I have no possible clue as to how they arrived at it!!!

It is : m sub 0 (v)/(c^2 (1 - v^2/ c^2))3/2)

I can see that the (1 - v^2/ c^2) should be to the negative 3/2 power but what about the 1/2 that should be a coefficient and and????? Any assistance would be greatly appreciated.