Show that the function f(x) = √|x-6| is not differentiable at x = 6. Find a formula for f'(x) and sketch its graph.
a) f'(x) = 1/2√|x-6|, not differentiable at x = 6
b) f'(x) = -1/2√|x-6|, not differentiable at x = 6
c) f'(x) = 0, differentiable at x = 6
d) f'(x) = √|x-6|, not differentiable at x = 6