## Calculus: Early Transcendentals (2nd Edition)

a. A function $f(x)$ is continuous from left at $x=a$ if $$\lim\limits_{x \to a^{-}} f(x)=f(a)$$. b. A function $f(x)$ is continuous from right at $x=a$ if $$\lim\limits_{x \to a^{+}} f(x)=f(a)$$