The numerator is the difference of two squares, hence the numerator is the product of a pair of conjugate binomials.
The denominator is a perfect square trinomial, factor it.
Once you have factored both numerator and denominator, eliminate identical factors in both numerator and denominator. Remember to set the eliminated factor equal to zero and solve for so that you know what value(s) to exclude from the domain of your resulting expression.
John
My calculator said it, I believe it, that settles it