20(a)
this is same as f(3), as we get to the same point coming to x = 3 from left or from right, and the limit is the same as the functional value at that point :
f(3) = 2
(b)
discontinuous at this point. the limit from the left is equal to the right, but is not equal to the value of the function.
“Removable discontinuity”.
the limit at x = 1 is -1, although f(1) = 1
(c)
discontinuous at this point. the limit from the left is equal to the right, but the functional value is not defined for this point.
“Removable discontinuity”.
the limit at x = -3 is 1, although f(-3) is undefined.
(d)
limit at x = 2 coming from the left (-) is 1.
(e)
the limit at x = 2 coming from the right (+) is 2.
(f)
therefore, the general limit at x = 2 does not exist (DNE).