Explain why each of the following integrals is improper. (a) \(\int_{1}^{4} \frac{d x}{x\ -\ 3}\) (b) \(\int_{3}^{\infty} \frac{d x}{x^{2}\ -\ 4}\) (c) \(\int_{0}^{1} \tan \pi x \ d x\) (d) \(\int_{-\infty}^{-1} \frac{e^{x}}{x} \ d x\) Equation Transcription: ? ? ? tan x dx ? dx Text Transcription: integral _1 ^4 dx/x-3 integral _3 ^infinity dx/x^2-4 integral _0 ^1 tan pi x dx integral _-infinity ^-1 e^x/x dx
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Textbook Solutions for Calculus: Early Transcendentals
Question
(a) If \(g(x)=\left(\sin ^{2} x\right) / x^{2}\), use a calculator or computer to make a table of approximate values of \(\int_{1}^{t} g(x) \quad d x\) for \(t=2,5,10,100,1000, \text { and } 10,000\). Does it appear that \(\int_{1}^{\infty} g(x) \quad d x\) is convergent?
(b) Use the Comparison Theorem with \(f(x)=1 / x^{2}\) to show that \(\int_{1}^{\infty} g(x) \quad d x\) is convergent.
(c) Illustrate part (b) by graphing \(f\) and \(g\) on the same screen for \(1 \leqslant x \leqslant 10\). Use your graph to explain intuitively why \(\int_{1}^{\infty} g(x) \quad d x\) is convergent.
Solution
The first step in solving 7.8 problem number trying to solve the problem we have to refer to the textbook question: (a) If \(g(x)=\left(\sin ^{2} x\right) / x^{2}\), use a calculator or computer to make a table of approximate values of \(\int_{1}^{t} g(x) \quad d x\) for \(t=2,5,10,100,1000, \text { and } 10,000\). Does it appear that \(\int_{1}^{\infty} g(x) \quad d x\) is convergent?(b) Use the Comparison Theorem with \(f(x)=1 / x^{2}\) to show that \(\int_{1}^{\infty} g(x) \quad d x\) is convergent.(c) Illustrate part (b) by graphing \(f\) and \(g\) on the same screen for \(1 \leqslant x \leqslant 10\). Use your graph to explain intuitively why \(\int_{1}^{\infty} g(x) \quad d x\) is convergent.
From the textbook chapter Improper Integrals you will find a few key concepts needed to solve this.
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