Chapter 2: Problem 14
Given the function \(f(x)=\left\\{\begin{array}{l}x^{2} \text { for } 0 \leq x<1 \\ \sqrt{x} \text { for } 1 \leq x \leq 2\end{array}\right.\) Compute \(\int_{0}^{2} \mathrm{f}(\mathrm{x}) \mathrm{dx}\).
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Chapter 2: Problem 14
Given the function \(f(x)=\left\\{\begin{array}{l}x^{2} \text { for } 0 \leq x<1 \\ \sqrt{x} \text { for } 1 \leq x \leq 2\end{array}\right.\) Compute \(\int_{0}^{2} \mathrm{f}(\mathrm{x}) \mathrm{dx}\).
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(a) Show that \(\int_{-1}^{1} \mathrm{f}(\mathrm{x}) \mathrm{d} \mathrm{x}=\mathrm{f}\left(\frac{-1}{\sqrt{3}}\right)+\mathrm{f}\left(\frac{1}{\sqrt{3}}\right)\) for \(f(x)=1, x, x^{2}\) and \(x^{3}\) (b) Let a and b be two numbers, \(-1 \leq \mathrm{a}<\mathrm{b} \leq 1\) such that \(\int_{-1}^{1} \mathrm{f}(\mathrm{x}) \mathrm{d} \mathrm{x}=\mathrm{f}(\mathrm{a})+\mathrm{f}(\mathrm{b})\) for \(\mathrm{f}(\mathrm{x})=1\), \(x, x^{2}\), and \(x^{3} .\) Show that \(a=-1 / \sqrt{3}\) and \(b=1 / \sqrt{3}\). (c) Show that the approximation \(\int_{-1}^{1} \mathrm{f}(\mathrm{x}) \mathrm{dx} \approx \mathrm{f}(-1 / \sqrt{3})+\mathrm{f}(1 / \sqrt{3})\) has no error when \(\mathrm{f}\) is a polynomial of degree atmost 3 .
(a) Make a conjecture about the value of the limit \(\lim _{k \rightarrow 0} \int_{1}^{b} t^{k-1} d t(b>0)\) (b) Check your conjecture by evaluating the integral and finding the limit. [Hint: Interpret the limit as the definition of the derivative of an exponential function]
Show that \(\int_{0}^{\infty} \sin \theta \mathrm{d} \theta\) and \(\int_{0}^{\infty} \cos \theta \mathrm{d} \theta\) are indeterminate.
Showthat \(\int_{0}^{\pi} \frac{\ell \mathrm{n}(1+\mathrm{a} \cos \mathrm{x})}{\cos \mathrm{x}} \mathrm{dx}=\pi \sin ^{-1} \mathrm{a},(|\mathrm{a}|<1)\)
Find \(\int_{0}^{2} f(x) d x\), where
\(f(x)=\left\\{\begin{array}{c}\frac{1}{\sqrt[4]{x^{3}}} \quad \text { for } 0
\leq x \leq 1 \\ \frac{1}{\sqrt[4]{(x-1)^{3}}}\end{array}\right.\) for \(1
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