Use a table of numbers to investigate \({\lim\limits_{x \rightarrow 0}}\dfrac{1-\cos x}{1+ \cos x}\).
In Problems 2 and 3, use a graph to investigate \(\lim\limits_{x\rightarrow c}f(x)\).
\(f(x)=\left\{ \begin{array}{l@{\quad}l@{\quad}l} 2x-5 & & \hbox{if }x\lt1 \\ 6-9x & & \hbox{if }x\geq 1 \end{array} \right.\) \(\quad\) at \(c=1\)
\(f(x)=\left\{ \begin{array}{l@{\quad}l@{\quad}l} x^{2}+2 & & \hbox{if }x\lt2 \\ 2x+1 & & \hbox{if }x\geq 2 \end{array} \right.\) \(\quad\) at \(c=2\)
For \(f(x)=x^{2}-3\):
In Problems 5 and 6, for each function find the limit of the difference quotient \(\lim\limits_{h\rightarrow 0}\dfrac{f(x+h)-f(x)}{h}\).
\(f(x)=\dfrac{3}{x}\)
\(f(x)=3x^{2}+2x\)
Find \(\lim\limits_{x\rightarrow 0}f(x)\) if \( 1+\sin x\leq f(x)\leq \vert x\vert +1\)
In Problems 8-22, find each limit.
\(\lim\limits_{x\rightarrow 2}\) \(\left( 2x-\dfrac{1}{x}\right)\)
\(\lim\limits_{x\rightarrow \pi } \left( x\cos x\right)\)
\(\lim\limits_{x\rightarrow -1}\left( x^{3}+3x^{2}-x-1\right)\)
\(\lim\limits_{x\rightarrow 0}\sqrt[3]{x( x+2) ^{3}}\)
\({\lim\limits_{x\rightarrow 0}}\) \([(2x+3) (x^{5}+5x)]\)
\({\lim\limits_{x\rightarrow 3}} \dfrac{x^{3}-27}{x-3}\)
\({\lim\limits_{x\rightarrow 3}}\left(\dfrac{x^{2}}{x-3}-\dfrac{3x}{x-3}\right)\)
\({\lim\limits_{x\rightarrow 2}}\dfrac{x^{2}-4}{x-2}\)
\({\lim\limits_{x\rightarrow -1}}\dfrac{x^{2}+3x+2} {x^{2}+4x+3}\)
\({\lim\limits_{x\rightarrow -2}} \dfrac{x^{3}+5x^{2}+6x}{x^{2}+x-2}\)
\({\lim\limits_{x\rightarrow 1}} \left(x^{2}-3x+\dfrac{1}{x}\right) ^{15}\)
\({\lim\limits_{x\rightarrow 2}}\dfrac{3-\sqrt{x^{2}+5}}{x^{2}-4}\)
\({\lim\limits_{x\rightarrow 0}} \left\{ \dfrac{1}{x}\left[ \dfrac{1}{(2+x)^{2}}-\dfrac{1}{4}\right] \right\}\)
\({\lim\limits_{x\rightarrow 0}} \dfrac{\left({x+3}\right) ^{2}-9}{x}\)
\({\lim\limits_{x\rightarrow 1}} [(x^{3}-3x^{2}+3x-1) (x+1) ^{2}]\)
In Problems 23-28, find each one-sided limit, if it exists.
\({\lim\limits_{x\rightarrow - 2^{+}}}\dfrac{ x^{2}+5x+6}{x+2}\)
\({\lim\limits_{x \rightarrow 5^{+}}}\dfrac{|x-5|}{x-5}\)
\({\lim\limits_{x\rightarrow 1^{-}}}\dfrac{|x-1|}{x-1}\)
\({\lim\limits_{x\rightarrow \,3/2^{+}}}\lfloor 2x\rfloor\)
\({\lim\limits_{x\rightarrow 4^{-}}}\dfrac{x^{2}-16}{x-4}\)
\({\lim\limits_{x\rightarrow 1^{+}}},\sqrt{x-1}\)
In Problems 29 and 30, find \(\lim\limits_{x\rightarrow c^{-}}f(x)\) and \(\lim\limits_{x\rightarrow c^{+}}f(x)\) for the given \(c\) Determine whether \(\lim\limits_{x\rightarrow c}f(x)\) exists.
\(f(x)=\left\{ \begin{array}{l@{\quad}l} 2x+3 & \hbox{if }x\lt 2 \\[3pt] 9-x & \hbox{if }x\geq 2 \end{array} \right.\) at \(c\)=2
142
\(f(x)=\left\{ \begin{array}{c@{ }c} 3x+1 & \hbox{if }x \lt 3 \\[3pt] 10 & \hbox{if }x=3 \\[3pt] 4x-2 & \hbox{if }x \gt 3 \end{array} \right.\) at \(c=3\)
In Problems 31-36, determine whether \(f\) is continuous at \(c\).
\(f(x)=\left\{ \begin{array}{c@{}c} 5x-2 & \hbox{if }x \lt 1 \\[3pt] 5 & \hbox{if }x=1 \\[3pt] 2x+1 & \hbox{if }x \gt 1 \end{array} \right.\) at \(c=1\)
\(f(x)=\left\{ \begin{array}{c@{}c} x^{2} & \hbox{if }x \lt -1 \\[3pt] 2 & \hbox{if }x=-1 \\[3pt] -3x-2 & \hbox{if }x \gt -1 \end{array} \right.\) at \(c=-1\)
\(f(x)=\left\{ \begin{array}{c@{}l} 4-3x^{2} & \hbox{if }x\lt0 \\[3pt] 4 & \hbox{if }x=0 \\[3pt] \sqrt{16-x^{2}} & \hbox{if }0 \lt x\leq 4 \end{array} \right.\) at \(c=0\)
\(f(x)=\left\{ \begin{array}{c@{}l} \sqrt{4+x} & \hbox{if }-4\leq x\leq 4 \\[3pt] \sqrt{\dfrac{x^{2}-16}{x-4}} & \hbox{if }x>4 \end{array} \right.\) at \(c=4\)
\(f(x) =\) \(\lfloor \,2x\rfloor\) at \(c=\dfrac{1}{ 2}\)
\(f(x)=|\,x-5\,|\) at \(c=5\)
A function \(f\) is defined on the interval \([-1,1]\) with the following properties: \(f\) is continuous on \([-1,1]\) except at \(0\), negative at \(-1\), positive at \(1\), but with no zeros. Does this contradict the Intermediate Value theorem?
In Problems 39-43 find all values \(x\) for which \(f(x)\) is continuous.
\(f(x)=\dfrac{x}{x^{3}-27}\)
\(f(x)=\dfrac{x^{2}-3}{x^{2}+5x+6}\)
\(f(x)=\dfrac{2x+1}{x^{3}+4x^{2}+4x}\)
\(f(x) =\sqrt{x-1}\)
\(f(x) =2^{-x}\)
Use the Intermediate Value Theorem to determine whether \( 2x^{3}+3x^{2}-23x-42=0\) has a zero in the interval \([3,4]\).
In Problems 45 and 46, use the Intermediate Value Theorem to approximate the zero correct to three decimal places.
\(f(x) =8x^{4}-2x^{2}+5x-1\) on the interval \(\left[0,1\right]\).
\(f(x) =3x^{3}-10x+9;\) zero between \(-3\) and \(-2\).
Find \({\lim\limits_{x\rightarrow 0^{+}}}\dfrac{|\,x\,|}{x}(1-x)\) and \({\lim\limits_{x\rightarrow 0^{-}}}\dfrac{|\,x\,|}{x}(1-x)\). What can you say about \({\lim\limits_{x\rightarrow 0}}\dfrac{|x|}{x} (1-x)\)?
Find \({\lim\limits_{x\rightarrow 2}}\left( \dfrac{x^{2}}{x-2}- \dfrac{2x}{x-2}\right)\). Then comment on the statement that this limit is given by \(\lim\limits_{x\rightarrow 2}\dfrac{x^{2}}{x-2}-\lim\limits_{x\rightarrow 2}\dfrac{2x}{x-2}\).
Find \({\lim\limits_{h\rightarrow 0}} \dfrac{f(x+h)-f(x)}{h}\) for \(f(x)=\sqrt{x}\).
For \(\lim\limits_{x\rightarrow 3}(2x+1)=7\), find the largest possible \(\delta\) that “works” for \(\epsilon =0.01\).
In Problems 51-60, find each limit.
\(\lim\limits_{x\rightarrow 0}\cos\) (tan x)
\(\lim\limits_{x\rightarrow 0}{\dfrac{{\sin {\dfrac{{x}}{{4}}}}}{{x}}}\)
\(\lim\limits_{x\rightarrow 0}\,\dfrac{\tan (3x) }{\tan ( 4x) }\)
\({\lim\limits_{x\rightarrow 0}}\dfrac{\cos {\dfrac{x}{3}-1}}{x}\)
\(\lim\limits_{x\rightarrow 0}\left( \dfrac{\cos x-1}{x}\right) ^{10}\)
\(\lim\limits_{x\rightarrow 0}{\dfrac{{e^{4x}-1}}{e^{x}{-1}}}\)
\(\lim\limits_{x\rightarrow \pi /2^{+}}\tan x\)
\(\lim\limits_{x\rightarrow -3}\dfrac{2+x}{( x+3) ^{2}}\)
\(\lim\limits_{x\rightarrow \infty }\dfrac{3x^{3}-2x+1}{x^{3}-8}\)
\(\lim\limits_{x\rightarrow \infty }\dfrac{3x^{4}+x}{2x^{2}}\)
In Problems 61 and 62, find any vertical and horizontal asymptotes of \(f\).
\(f(x)=\dfrac{4x-2}{x+3}\)
\(f(x)=\dfrac{2x}{x^{2}-4}\)
Let \(f( x) =\left\{ \begin{array}{c@{}c} \dfrac{\tan x}{2x} & \hbox{if }x\neq 0 \\ \dfrac{1}{2} & \hbox{if }x=0 \end{array} \right.\). Is \(f\) continuous at \(0\)?
Let \(f( x) =\left\{ \begin{array}{c@{}c} \dfrac{\sin ( 3x) }{x} & \hbox{if }x\neq 0 \\ 1 & \hbox{if }x=0 \end{array} \right.\). Is \(f\) continuous at \(0\)?
The function \(f( x) =\dfrac{\cos \left( \pi x+\dfrac{\pi }{2}\right) }{x}\) is not defined at \(0\). Decide how to define \(f( 0)\) so that \(f\) is continuous at \(0\).
Use an \(\epsilon\) - \(\delta\) argument to show that the statement \(\lim\limits_{x\rightarrow -3} (x^{2}-9) =-18\) is false.
If \(1-x^{2}\leq f(x)\leq\) cos \(x\) for all \(x\) in the interval \(-\dfrac{\pi }{2} \lt x \lt \dfrac{\pi }{2}\), show that \(\lim\limits_{x\rightarrow 0}f(x)=1\).