Chapter 2: Problem 58
$\begin{aligned} f(x) &=\frac{4-x^{2}}{\left|4 x-x^{3}\right|} \\ &=
\begin{cases}\frac{-\left(4-x^{2}\right)}{\left(4 x-x^{3}\right)}, & x>2 \\\
\frac{4-x^{2}}{4 x-x^{3}}, & 0
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Chapter 2: Problem 58
$\begin{aligned} f(x) &=\frac{4-x^{2}}{\left|4 x-x^{3}\right|} \\ &=
\begin{cases}\frac{-\left(4-x^{2}\right)}{\left(4 x-x^{3}\right)}, & x>2 \\\
\frac{4-x^{2}}{4 x-x^{3}}, & 0
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Correction $\rightarrow f(x)=\frac{1-\cos x(\cos 2 x)^{1 / 2} \cos (3 x)^{1 / 3}}{x^{2}}$ Sol using L-Hospital's Rule $\begin{aligned} & \lim _{x \rightarrow 0}(\sin x)(\cos 2 x)^{1 / 2}(\cos 3 x)^{1 / 3}+\cos x(\cos 3 x)^{1 / 3} \\ \lim _{x \rightarrow 0} f(x)=& \frac{\sin 2 x}{\sqrt{\cos 2 x}+\cos x(\cos 2 x)^{1 / 3} \frac{\sin 3 x}{(\cos 3 x)^{2 / 3}}}{2} \\\=& \lim _{x \rightarrow 0}\left[\frac{1}{2}+1+\frac{3}{2}\right]=3 \end{aligned}$
$\mathrm{f}(\mathrm{x})=\lim _{\mathrm{n} \rightarrow \infty} \frac{(2 \sin \mathrm{x})^{2 \mathrm{n}}}{3^{\mathrm{n}}-(2 \cos \mathrm{x})^{2 \mathrm{n}}}\( \)\Rightarrow \lim _{n \rightarrow \infty} \frac{(2 \sin x)^{2 n}}{1-\left(\frac{2}{\sqrt{3}} \cos x\right)^{2 n}}$ \(\mathrm{f}(\mathrm{x})\) is discontinuous whenever \(2 \sin x=\pm 1 \& \frac{2}{\sqrt{3}} \cos x=\pm 1\) \(\Rightarrow \mathrm{x}=\mathrm{n} \pi \pm \frac{\pi}{6}\)
$f(x)=\left\\{\begin{array}{l}{\left[x^{2}+e^{\frac{1}{2-x}}\right]^{-1}, x>2} \\\ k & , \quad x=2 .\end{array}\right.$ $\lim _{x \rightarrow 2^{-}}\left[x^{2}+e^{\frac{1}{2-x}}\right]^{-1}=\frac{1}{4}$
A) $f(x)= \begin{cases}\frac{1+a \cos x}{x^{2}}, & x<0 \\ b \tan \left(\frac{\pi}{[x+3]}\right), & x \geq 0\end{cases}$ \(\lim _{x \rightarrow 0^{-}} \frac{1+a \cos x}{x^{2}}\) Exists if \(\mathrm{a}=-1\). Then limit is \(\frac{1}{2}\). $\lim _{x \rightarrow 0^{-}} b+a \frac{\pi}{3}=\frac{1}{2} \Rightarrow b=\frac{1}{2 \sqrt{3}} \Rightarrow[a-2 b]=-2$ Hence, \(\mathrm{R}\) is correct. B) $\lim _{x \rightarrow-\frac{\pi}{2}}(-2 \sin x)=2$ \(\lim _{x \rightarrow-\frac{\pi^{*}}{2}}(a \sin x+b)=+b-a\) \(\lim _{x \rightarrow \frac{\pi}{2}}(\operatorname{asin} x+b)=a+b\) \(\lim _{x \rightarrow \frac{\pi}{2}} \cos x=0\) Hence \(\mathrm{P}, \mathrm{Q}\) is correct. C) $\lim _{x \rightarrow \frac{\pi}{2}}\left(\frac{3}{2}\right)^{\frac{\cos 3 x}{\cot 2 x}}=1$ $\lim _{x \rightarrow \frac{\pi^{-}}{2}}(1+|\cos x|)^{\frac{a|t a n x|}{b}}=e^{\frac{\lim _{T}}{x} \frac{a \sin x \mid}{b}}=e^{\frac{a}{b}}$ \(f\left(\frac{\pi}{2}\right)=\frac{\pi}{2}+3\) \(\Rightarrow \quad a=0\) D) \(\lim _{x \rightarrow 0^{0}} a+\frac{\sin [x]}{x}=a\). \(\lim _{x \rightarrow 0} b+\left[\frac{\sin x-x}{x^{3}}\right]=b-1\) \(f(0)=2\) \(\Rightarrow \mathrm{a}=2, \quad \mathrm{~b}=3\) So, \(\mathrm{T}\) is correct.
\(\lim _{x \rightarrow 0^{\prime}} \frac{b e^{x}-\cos x-x}{x^{2}}\) For limit to exist, \(b=1\) \(\lim _{x \rightarrow 0^{+}} \frac{e^{x}-\cos x-x}{x^{2}}=1=a\) $\lim _{x \rightarrow 0^{-}} \frac{2\left(\tan ^{+} e^{x}-\frac{\pi}{4}\right)}{x}=1$
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