0:00 / 0:00

L'Hospital's Rule

*used to handle indeterminate forms of a limit

Indeterminate Forms

00\frac{0}{0}, \frac{\infty}{\infty}, 0×0\times\infty, \infty-\infty, 11^{\infty}, 0\infty^0, 000^0

L'Hopital's Rule

Criteria:
  • ff and gg are differentiable and g(x)0g'\left(x\right)\ne0 and
  • limxaf(x)g(x)=00   or   ±±\lim_{x\to a}\frac{f\left(x\right)}{g\left(x\right)}=\frac{0}{0}\ \ \ or\ \ \ \frac{\pm\infty}{\pm\infty}
Then limxa f(x)g(x)=limxa f(x)g(x)\lim_{x\to a}\ \frac{f\left(x\right)}{g\left(x\right)}=\lim_{x\to a}\ \frac{f'\left(x\right)}{g'\left(x\right)}.

Other Indeterminate forms


Practice: L'Hospital's Rule

Determine limx0tanxex1\displaystyle \lim_{x\rightarrow0}\frac{\tan x}{e^x-1}.

Practice: L'Hospital's Rule

Evaluate limx x3 sin(1x2)\displaystyle \lim_{x\to\infty}\ x^3\ \sin\left(\frac{1}{x^2}\right).

Practice: L'Hospital's Rule

Evaluate limx0+(e1x)1lnx\lim_{x\rightarrow0^+}\left(e^{\frac{1}{x}}\right)^{^{\frac{1}{\ln x}}}.