Theory

• Rational function domain: exclude values that make denominator $0$.
• To find range, set $y=f(x)$ and solve for $x$; values of $y$ that make the solved expression impossible are excluded.
• One-to-one: show $f(x_1)=f(x_2)\Rightarrow x_1=x_2$.
• Onto: check if range equals co-domain.