005 Sample Final A, Question 2

Question Find the domain of the following function. Your answer should be in interval notation $f(x)={\frac {1}{\sqrt {x^{2}-x-2}}}$

Foundations:
1) What is the domain of ${\frac {1}{\sqrt {x}}}$?
2) How can we factor $x^{2}-x-2$?
Answer:
1) The domain is $(0,\infty )$. The domain of ${\frac {1}{x}}$ is $[0,\infty )$, but we have to remove zero from the domain since we cannot divide by 0.
2) $x^{2}-x-2=(x-2)(x-1)$