I'm having a bit of trouble with the following problems. Any help would be greatly appreciated.

Are the following functions Lipschitz continuous near 0? If yes, find a Lipschitz constant for some interval containing 0.

a) f(x) = 1/(1-x^2)

For this one, I think it's Lipschitz near 0. I have

|f(x)-f(y)| = [(x+y)/(1-x^2)*(1-y^2)] * (x-y)

I'm not sure how to find the constant, though.

b) f(x) = x^2 sin(1/x)

I don't think this one is Lipschitz near 0, but I don't know how to show it.