Question

Which domain restrictions apply to the rational expression?

Answer 1

1) it must be fulfilled that the denominator is different from zero, then for this expression

x^2 -9  ⇒ x^2-3^2 = (x-3)(x+3)⇒ (x-3)(x+3) = 0 ⇒ x = 3 o x = -3 , the dominium is all numbers reals except 3 and -3