Chapter 2: Problem 21
Show that the inequalities \(0.692 \leq \int_{0}^{1} x^{x} d x \leq 1\) are valid.
Chapter 2: Problem 21
Show that the inequalities \(0.692 \leq \int_{0}^{1} x^{x} d x \leq 1\) are valid.
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Get started for freeProve the inequalities: (i) \(\int_{1}^{3} \sqrt{x^{4}+1} d x \geq \frac{26}{3}\)(iii) \(\frac{1}{17} \leq \int_{1}^{2} \frac{1}{1+x^{4}} \mathrm{dx} \leq \frac{7}{24}\).
Here is an argument that \(\ln 3\) equals \(\infty-\infty\). Where does the argument go wrong ? Give reasons for your answer. \(\ln 3=\ln 1-\ln \frac{1}{3}\) \(=\lim _{b \rightarrow \infty} \ln \left(\frac{b-2}{b}\right)-\ln \frac{1}{3}\) \(=\lim _{b \rightarrow x}\left[\ln \frac{x-2}{x}\right]_{3}^{b}\) \(=\lim _{b \rightarrow \infty}[\ln (x-2)-\ln x]_{3}^{b}\) \(=\lim _{b \rightarrow \infty} \int_{3}^{b}\left(\frac{1}{x-2}-\frac{1}{x}\right) d x\) \(=\int_{3}^{\infty}\left(\frac{1}{x-2}-\frac{1}{x}\right) d x\) \(=\int_{3}^{\infty} \frac{1}{x-2} d x-\int_{3}^{\infty} \frac{1}{x} d x\) \(=\lim _{b \rightarrow \infty}[\ln (x-2)]_{3}^{b}-\lim _{b \rightarrow \infty}[\ln x]_{3}^{b}\) \(=\infty-\infty .\)
Show that \(\int_{0}^{1} \frac{\ell n\left(1-a^{2} x^{2}\right)}{x^{2} \sqrt{\left(1-x^{2}\right)}} d x\) \(=\pi\left[\sqrt{1-a^{2}}-1\right],\left(a^{2}<1\right)\)
Compute (a) \(\lim _{t \rightarrow 0+} \int_{t}^{1} \frac{1}{x} \mathrm{dx}\) (b) \(\lim _{t \rightarrow 1-} \int_{0}^{t} \tan \frac{\pi}{2} x d x\). How does the result give insight into the fact that neither integrand is integrable over the interval \([0,1] ?\)
Prove that \(\lim _{\lambda \rightarrow \infty} \int_{0}^{\infty} \frac{1}{1+\lambda x^{4}} d x=0\).
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