1. Suppose that f(a)=g(a) and the left-hand derivative of f at a equals the right-hand derivative of g at a. Define h(x)=f(x) for x<=a, and h(x)=g(x) for x>=a. Prove that h is differentiable at a. 2. Let 0<B<1. Prove that if f satisfies /f(x)/ >= /x/^B and f(0)=0, then f is not differentiable at 0. the sign / / is absolute value. 3. Let f(x)=x^n for x>=0 and let f(x)=0 for x<=0. Prove that f^(n-1)exists and find a formula for it, but that f^(n) (0) does not exist. Can someone help me out with these problems? thx a lot!!!