I'm going to assume that you meant the following:
(x-1)
---------------
x^2-3x+2
Factoring the denominator, we get:
(x-1)
------------
(x-1)(x-2)
Notice that we have x-1 in both the numerator and the denominator. This factor cancels. HOWEVER: x can still not equal 1, which would lead to div. by zero. With the factor x-1 cancelled, we have 1 / (x-2). As x approaches 1 from either side, y approaches 1 / (1-2), or 1 / (-1), or -1. Thus, the limit exists and is -1.