Question 671953
Factor the denominator. Set each factor to 0. Those are what make you undefined. Be sure to plug each "solution" into the numerator, because if you get 0/0, that's actually okay as that is indeterminate, not undefined.

{{{y^2-4 = (y+2)(y-2)}}} --->  y=-2,2

When I plug in -2 or 2 I don't get 0 in the numerator so it is undefined at y = -2,2