Let f be the function given by f of x equals begin quantity x minus 12 end quantity over begin quantity x squared minus 25 times x plus 156 end quantity. Part A: Graph the function f using graphing technology. What is an appropriate horizontal scale and vertical scale for the viewing window? (5 points) Part B: Find the limit of f of x as x approaches c or explain why the limit of f of x as x approaches c does not exist for each of the values c = 12, 13, and 14. Make sure to include reasoning using correct limit notation. (25 points)