Question 1: (25 pts.) [5 points each] Find the limit of the following expressions (if they exist); simplify completely your final answer and show all work and steps. Results given

without any justifications will not receive credits. \text { a) } \lim _{x \rightarrow 5} 4^{\left(\frac{x^{2}-2 x-15}{x^{2}-25}\right)}