What is the domain of f(x)= (x^2+18x+18 ) / ( x^2+9x+20)?

1 Answer
Mar 19, 2018

x inRR

Explanation:

If we look at the numerator and denominator, they are both quadratics, which are defined and continuous for all real numbers.

Defined and continuous <=> x inRR

We can plug in any value for x and get a value for f(x). It doesn't matter that it's a fraction- even if x is zero, we get a value, 9/10.