### Instruction: For how many values of $x$ is the expression $\frac{x^2-9}{(x^2+2x-3)(x-3)}$ undefined?### Response: To find the values of $x$ that make the expression undefined, I need to look at the denominator and see when it is equal to zero.
I can factor the denominator as $(x+3)(x-1)(x-3)$.
This means that the expression is undefined when $x=-3$, $x=1$, or $x=3$.