Considering the picture attached, the distance to Cascade Falls is written in mixed fraction and the question wants it expressed in decimal. is same as 1 divided by 2 which is 0.5 hence the fall is 3+0.5=3.5 miles
It is not differentiable at x=1 since the slope of the tangent line as x -> 1 from the right is 1 while the slope of the tangent line as x->1 from the left is -1
