Question

How many vertical asymptotes exist for this function?

Answer 1

Remember that to find the vertical asymptotes of rational functions, we just need to set the denominator equal to zero and solve for the variable, in this case $x$, so lets do it:
$(x-4)(x+1)=0$
$x=4,x=-1$

As you can see, our rational functions has 2 vertical asymptotes: $x=4$ and $x=-1$