The example Desmos link provided is a Calculus Limit where direct substitution of x=3 results in 0/0 (Indeterminate Form) = a Hole in the graph at (3,-4) found by multiplying by the conjugate, and eliminating dividing by zero

I believe firmly in using the Desmos program to help students see visually that they are getting the steps correct old school style, while simultaneously viewing the graph for deeper understanding