What happens if you are checking a solution for the rational expression and find that it makes one of the denominators in the expression equal to zero?

Answer 1

It means that the expression is undefined for that particular solution.

e.g.
suppose we have the expression (x+5)/(x^ - 4) and we are given that x = 2

we could get
7/0 , which is undefined

so we would state the expression as
(x+5)/(x^2 - 4) , x ≠ ± 2