Question

what is the LCD of x-3, x+3, and $x^2-9$

Answer 1

The least common denominator is one, since all of these numbers are actually whole numbers. They're actually all $\frac{x-3}{1} \frac{x+3}{1} \frac{x^2-9}{1}$
If you mean the greatest common factor, then it's obviously $x$