Chapter 4 : Applications of Derivatives

An absolute maximum is also a local maximum. Being the largest value overall, it is also the largest value in its immediate neighborhood. Hence, a list of all local maxima will automatically include the absolute maximum if there is one. Similarly, a list of all local minima will include the absolute minimum if there is one.


L'Hôpital's Rule

a. First Form

Suppose that f(a)=g(a)=0, that f'(a) and g'(a) exist, and that g'(a)
eq 0. Then 

lim_{x
ightarrow a}frac{f(x)}{g(x)}=frac{f'(a)}{g'(a)}

b. Stronger Form

Suppose that f(a)=g(a)=0, that f and g  are differentiable on an open interval I containing a, and that g'(x)
eq0 on if x
eq a.Then

lim_{x
ightarrow a}frac{f(x)}{g(x)}=frac{f'(a)}{g'(a)},

assuming that the limit on the right side exists.

Proof of L'Hôpital's Rule


Find  lim_{x
ightarrow infty }(xsinfrac{1}{x})

Solution 

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原文地址:https://www.cnblogs.com/chintsai/p/11829259.html