How do I ';Find all numbers that must be excluded from the domain of the rational expression?';?

This is the actual problem:It is a fraction too. Fractions always confuse me.


numerator=x-3 denominator=x^2+11x+24


Thank you.How do I ';Find all numbers that must be excluded from the domain of the rational expression?';?
The denominator factorizes: (x + 3)(x + 8).


I suppose the question means that zero is not allowed in the denominator because that makes the expression infinite, so x = -3 and x = -8 are excluded.