Math=absolute gibberish to me...

Two questions:

Determine whether function f defined by
f(x) = 2 x 2 for x <= 1 and
f(x) = 2 sqrt(x) for x > 1
is differentiable at x = 1.

and



Find all values of x for which function f defined by
f(x) = sqrt (x 2 - 2 x + 1)
is not differentiable.