Is the question:
What are the values of a and b that make f(x) a continuous function?
Ok, then you need the limit of the function to be the same when x approaches 1 from the left and from the right, and also the same when x approaches 3 from the left and from the right.
This means
when x = 1 and when x = 3.
Substituting those values of x into the equation, we get these two equations:
Simplifying, we get
You are correct.