Please help with number 12. I need to show all work but I have no idea how to do that.

11-12 Sketch the graph of the function and use it to determine the values of a for which limz-+a f (x) exists. 11. f (*) = *-1 if0 <: ifx>1 Answer 12. if & -1 f() = if -1:$2 (c-1) ifa > 2