l'Hospital's rule

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Intros
Lessons
  1. Evaluating the limit of the form:
    limโก\limx →c c f(x)g(x)\frac{f(x)}{g(x)}
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Examples
Lessons
  1. Evaluating the limit.
    Find:
    1. limโก\limx →1 1 lnโกxxโˆ’1\frac{\ln x}{x-1}
    2. limโก\limx →โˆž \infty lnโกxxโˆ’1\frac{\ln x}{x-1}
Topic Notes
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Remember that one tricky Limits section that required intense algebraic manipulation to avoid getting 0/0 or infinity/infinity limits? We will now revisit it again, but with the knowledge of derivatives. In this section, we will learn how derivatives enable us to efficiently evaluate the limits of a function using the "L'Hospital's rule".
Note *l'Hôpital's Rule applies to 2 types of indeterminate forms:

type 00\frac{0}{0} (that is, limโก\limx →c c f(x)=0f(x)=0 and limโก\limx →c cg(x)=0g(x)=0)
or
type โˆžโˆž\frac{\infty}{\infty} (that is, limโก\limx →c c f(x)=ยฑโˆžf(x)=\pm \infty and limโก\limx →c cg(x)=ยฑโˆžg(x)=\pm \infty)

Then according to l'Hôpital's Rule: limโก\limx →c c f(x)g(x)=\frac{f(x)}{g(x)}= limโก\limx →c c fโ€ฒ(x)gโ€ฒ(x)\frac{f'(x)}{g'(x)}