Analyzing Continuity and Differentiability of f(x) at x=1 & x=3

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Homework Statement


f(x) is a piecewise function defined as:

|x-3| x>=1
\frac{x^2}{4}-\frac{3x}{2}+\frac{13}{4} x<1

Discuss the continuity and differentiability of this funtion at x=1 and x=3

Homework Equations





The Attempt at a Solution


At x=3, this function is continuous but not differentiable, being a modulus funtion. But how is is continuous and differentiable at x=1? Putting limit x=1 in the above funtion doesn't give you the same value for both the parts!
 
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Look at the limit as x->1 from both sides of the function and the derivative of the function. What do you get as answers to these four questions?
 
The func is cont. at x=1. Plug in 1 again, in both expression
 
Whoa! I really feel like an idiot now. I messed up the arithemetic.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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