1)Is the function f(x) = |3x - 9| differentiable at x = 3?

2) Is the function

f(x) = {5x - 5 , x < 2

{2x + 1, x>=2

differentiable at x = 2?

for 2, when you sub in x=2, both equal 5, does that mean it is or is not differentiable?

and for 1 i'm not sure how you go about it