# Science:Math Exam Resources/Courses/MATH100/December 2016/Question 09 (a) (iii)/Hint 1

The line ${\displaystyle y=b}$ is the horizontal asymptote of the function ${\displaystyle y=f(x)}$ if ${\displaystyle {\underset {x\to \infty }{\lim }}f(x)=b}$ or ${\displaystyle {\underset {x\to -\infty }{\lim }}f(x)=b}$ .