For what real values of a is the expression \(\frac{a+3}{a^2-4}\) undefined? List your answers in increasing order separated by commas.
This expression will be undefined only when the denominator is zero
---> a2 - 4 = 0 ---> (a - 2)(a + 2) = 0
So, the two times that the expression is undefined occurs when a = 2 or a = -2.