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Chapter 5, Answers

Chapter 5

5.1.4

  1. \(\frac{x^9}{9}-x+C \).
  2. \( -2e^{-2x} + 6x – 3\tan 2x + C \).
  3. \( \frac{1}{2}(\cosh 2x – \cos 2x) +C \).
  4. \( \pi \tan 6x +C \).
  5. \( x\left (1-\frac{9}{4}\sqrt[3]{x}+\frac{9}{5}x \sqrt[3]{x}-\frac{1}{2}x\right ) +C \).
  6. \(\frac{1}{\pi}\left (-2\cos \pi x + \cot \pi x\right ) +C \).
  7. \(-x+4\arctan x +\arcsin x+C \).
  8. \(x- 2\tan \frac{x}{2} +\frac{1}{\pi }\left (\sin \pi x – \cos \pi x\right ) +C \).
  9. \(-\frac{2}{3}\csc 3x+C\).
  10. \(x^x (\ln x +1)+2^{(x^2+1)} x \ln 2\).
  11. \(\frac{1}{2\sqrt{1-x}} + \sec^{-1}\sqrt{x}\).
  12. \(\frac{x (6 \ln x+3)}{4\ln 2}\).
  13. \(\frac{x e^{x^2} (2 x^4+3 x^2+2)}{(1+x^2)\,\sqrt{1+x^2}}\).
  14. (a)–(c) False.

5.1.6

  1. \(\frac{2}{3}\sqrt{x^3}+x+\frac{1}{3}\).
  2. \(\frac{1}{2}\tan 2x- x-3\).
  3. \(2\sin^{-1}x – \frac{4\pi}{3}\).
  4. \(x+3\tan^{-1}x + \pi + \frac{1}{\sqrt{3}}\).
  5. \(\frac{2}{\pi}\sin \pi x -\frac{\sqrt 2}{\pi}\).
  6. \(\frac{x}{2e^2}-2x+\frac{1}{4}e^{-2x}-\frac{3}{4e^2}+3\).
  7. \(\frac{x}{\pi}-x -\frac{1}{\pi^2}\cos \pi x -\frac{3}{2\pi} +\frac{5}{2}\).
  8. \(ex+\frac{x}{e}-\ln x+e^2+e\).
  9. \(-\frac{x}{\pi}-\frac{3}{2}\sin 2x – \cos 2x -\frac{1}{2}\).
  10. \(\sin 2 x – \cos 2 x -1\).

5.1.8

  1. \(\frac{1}{4}(2t- \sin 2t)\).
  2. \(-4.9 t^2+12.8 t+2.1\) m.
  3. \(-\frac{1}{\pi} t +\frac{1}{\pi}\tan t+1 \) cm.
  4. \(t+\arctan t – \frac{\pi}{4} \).

5.1.10

  1. \(\frac{1}{2}\left (1+\sqrt[3]{x^2}\right )^3+C\).
  2. \(\frac{1}{\pi}\ln \sec \pi x +C\).
  3. \(\frac{1}{9}\arctan^3 3x+C\).
  4. \(-\frac{1}{3}\sqrt{\cos^3 e^{2x}}+C\).
  5. \(\frac{1}{12}\ln^4x^3 + C\).
  6. \(2\tan \sqrt{x} + C\).
  7. \( -2e^{\cos(x/2)}+C\).
  8. \(\frac{1}{\pi}e^{\sin^2\pi x}+C\).
  9. \(\frac{1}{4}\arcsin^2(2x)+C\).
  10. \(\frac{1}{8}\ln(1+4x^2)+ \frac{1}{4}\arctan^2(2x)+C\).
  11. \(\frac{1}{2}\arctan e^{2x}+C\).
  12. \(\frac{1}{3}\arcsin x^3 + \frac{1}{12}\arcsin^4 x^3+C\).
  13. \(e^x-e^{-x} + C\).
  14. \(w-\frac{\sqrt{2}}{\pi}\cos \pi x + C\).
  15. \(-\frac{1}{4\pi}(\tan \pi x + \cot \pi x)+ C\) or \(-\frac{1}{2\pi}\csc 2\pi x+C\).

5.2.2

  1. (a) \(\frac{1}{4}x^4+x^3+x^2 + C\); (b) \(\frac{1}{4}x^2 (x + 2)^2 + D\).
  2. \(-\frac{32}{3\ln^2x^3} +C\).
  3. \(x-\frac{1}{8}\sin 4x + \frac{1}{16}\sin 4x + C\).
  4. \(\frac{\ln^4 x}{4\ln^3x} + C\).
  5. \(\frac{1}{\ln 2}2^{\sin^2x} + C\).
  6. \(\frac{1}{8}\arcsin^2 4x + C\).
  7. \(\frac{3}{16}\left (1+\sqrt[3]{x^4}\right )^4\).
  8. \(-\frac{1}{2\sqrt{t(1-t)}} \).
  9. \(\frac{e^{\sqrt{z}}\left (2 (z^2+1) + (z^2\sqrt{z} – 2 z^2 + \sqrt{z}\right ) \ln z }{x\sqrt{(1+z^2)^3}}\).
  10. \(-\frac{2u}{(u^2+1)^2}\).
  11. \(\sin^t(\pi t) (\pi t \cot\pi t+\ln \sin \pi t) \).
  12. \(2^{2+u^2}\ln 2\).
  13. \(\frac{1}{8}\frac{1}{ \sqrt{1+x}}\frac{1}{ \sqrt{1+\sqrt{1+x}}}\frac{1}{\sqrt{1+\sqrt{1+\sqrt{1+x}}}}\).
  14. \(\frac{1}{2\pi}\frac{1}{\cos^2\pi x}+C\), \(\frac{1}{2\pi}\sec^2\pi x+C\), \(\frac{1}{2\pi} \tan^2\pi x+C\). Why are these three answers compatible?
  15. \(-\frac{1}{2\pi}\cos^2\pi x + C\); \(\frac{1}{2\pi}\sin^2\pi x + C\); \(-\frac{1}{4\pi}\cos 2\pi x + C\). Why are these three answers compatible?
  16. \(\frac{1}{2\pi}\csc^2 \pi x+C\), \(-\frac{1}{2\pi}\cot^2 \pi x+C\), \(-\frac{1}{2\pi \sin^2\pi x}+ C\).

5.2.6

  1. \(\sin x^2\).
  2. \(-\ln x\).
  3. \(2x \,\sqrt{1+x^8} – 2\sqrt{1 + 16x^4}\).
  4. \(\frac{x\,\sqrt{x}}{2(1+x)} – \tan^4x\).
  5. \(e^{-e^{2x}+x}- \frac{x^{-x}(\ln x + 1)}{2\sqrt{x\ln x}}\).
  6. \(\frac{\sin x}{x} – \frac{x}{2\arcsin(x/2)\sqrt{4-x^2}}\).
  7. \(-|\sin x|\sin x – \sqrt{1-x^2}\).
  8. \(\frac{1}{2\sqrt{\tan x}}\).
  9. (a) \(f(x)= -\frac{3}{\sqrt{1-9x^2}}\), \(c=-\frac{\pi}{3}\); (b) \(f(x)= \frac{1}{3x}\), \(c=-\frac{2}{3}\).
  10. (a) \(f(x)= 2\sin x\), \(c\) can be any value \(c=\frac{(2n+1)\pi}{2}\), \(k \in \mathbb{Z}\); (b) \(f(x)= \frac{\arctan \sqrt{x}}{(1+x)\,\sqrt{x}}\), \(c=\frac{1}{3}\).

5.3.2

  1. (b) \(e^{3/4}-1\).
  2. (b) \(\frac{\pi^2}{9}\).
  3. (b) \(\frac{12}{5}\).
  4. (b) \(\frac{17\pi}{96}\).
  5. (b) \(\frac{1}{\sqrt{2}\pi}\).
  6. (b) \(\frac{33}{4}\).
  7. (b) \(6 \).
  8. (b) \(\pi\).
  9. \(f(x) = \frac{1}{x^2}\) is not continuous on \([-1,2]\).
  10. \([2,4]\) is not in the domain of \(f(x)= \frac{1}{\sqrt{1-x^2}}\).
  11. \(2^x\) is not an antiderivative of \(2^x\).
  12. The antiderivative to use is \(F(x) =\ln |x|\).
  13. (a) \(0 \); (b) \(\frac{8}{3} \).
  14. (a) \(-2 \); (b) \(\frac{2}{3\pi}(6\sqrt{3}+\pi) \).
  15. (a) \(-\frac{1}{8}+\frac{e^4}{2}-e(2+\ln 2) \); (b) \(\frac{1}{8}(1-16e+4e^4+8e \ln 2 ) \).
  16. (a) \(-\frac{3}{2}+2\ln 2 \); (b) \(\frac{1}{2}\).
  17. \(\frac{8}{3}\).
  18. \(\frac{4\sqrt{2}}{3}\).
  19. \(\sqrt{3}-\sqrt{2}\).
  20. \(\frac{4}{7}\).
  21. \(\frac{242}{5}\).
  22. \(\sqrt{3}-\frac{\pi}{3}\).
  23. Area of a semicircle with \(r=2\): \(A=2\pi\).

5.3.4

  1. (a) \(-3\) m; (b) \(5\) m.
  2. (a) \(-24 \) m; (b) \(\frac{111}{4} \) m.
  3. (a) \( 0\) m; (b) \(\frac{3\sqrt{3}}{2\pi} \) m.
  4. (a) \(0 \) m; (b) \( \frac{1}{\pi}\) m.

5.4.2

  1. \(\frac{1}{12}(2 + x^4)^3+C \).
  2. \(\frac{1}{3}\tan^3t+C\).
  3. \(-\frac{7}{64\pi}\).
  4. \(\frac{1}{2}\sin e^{2w}+C \).
  5. \(\frac{15}{8}\).
  6. \(-\frac{\pi^2}{24}\).
  7. \(\frac{\pi^3}{24}\left (\frac{1}{8}+\frac{1}{27}\right )\).
  8. \(\frac{e-1}{\pi} \).
  9. \(-\frac{1}{3\pi}\cot^3x+C \).
  10. \( \frac{1}{\ln 2} 2^{\sqrt{t}+1} + e^{e^t} +C\).
  11. \(\frac{1}{\pi} \left (\sin \pi x -\cos \pi x\right ) +C\)
  12. \( \frac{3}{2}\ln(1+x^2)+4x – 2\arctan x + C\).

5.4.4

  1. \(\frac{3}{8}(x^2+1)\sqrt[3]{x^2+1} + C\).
  2. \( \frac{1}{2}\arctan x^2+ C\).
  3. \( -\frac{1}{3}\ln \left [\cos e^{3x}\right ]+ C\).
  4. \(2 \sec\sqrt{t}+ C\).
  5. \( \frac{1}{4}\arctan^2 2t + C\).
  6. \( -\frac{1}{\pi}\arcsin e^{\cos \pi x} + C\).
  7. \(-\frac{1}{\pi}\arctan (\cos^2\pi x) +C\).
  8. \( \frac{1}{3}\arcsin\left (\ln x^3\right )+ C\).
  9. \(\frac{1}{2}(x^3+1)^(2/3)+C\).
  10. \(\frac{1}{2}(e^{2x}+e{-2x}) + C \)
  11. \(\frac{1}{3}\ln|\cos e^{3x} + C\)
  12. \(-\frac{3}{2}\cot^2\sqrt[3]{x} + C\)
  13. \( \frac{1}{3}\sqrt{ \ln^2 ( x^3)} + C\)
  14. \(\frac{1}{2\pi}\arctan (\sin^2\pi x) +C\).
  15. \(\frac{175}{64}\).
  16. \(\frac{1}{24}\pi(4+\pi) \).
  17. \( \frac{1}{12}\).
  18. \( \frac{\pi^3}{72}\).
  19. \(\frac{1}{6}(3\sqrt{3}-1) \).
  20. \(\left (\sqrt{e} -1\right )\sqrt[4]{e} \).

5.5.2

  1. \(\frac{2}{3}\ln|3x+4| +C\)
  2. \(6 (x + 1) – 7 \ln |x+1|+C\)
  3. \(2 x^3 – 3 x^2 + 9 x – 11\ln|x+1|+C\).
  4. \(x+\frac{1}{2}e^2x+C\).
  5. \(\frac{2}{3}\sin^3\theta -\ln|\sin \theta+2|+C\).
  6. \(x^3-x +\frac{1}{2} \ln(x^2+1)+2 tan^{-1} x + C\).
  7. \(3 x^2-\frac{3}{2} \ln(x^2+1)-2 tan^{-1} x + C\).
  8. \(\ln^2 x – 6 \ln x + \frac{13}{2} \ln|2 \ln x + 3| + C\).

5.5.4

  1. \(\frac{2}{27} \sqrt{3 x-1} (6 x-5)\).
  2. \(\frac{4}{15}\,\sqrt{(\sqrt{x}+2)^3} \,(3\sqrt{x}-4)+ C\).
  3. \(-\frac{6 x^2+1}{48 \left(2 x^2+1\right)^3}+C\).
  4. \(\frac{1}{15} \sqrt{\left(2 x-1\right)^3}\left (3x+1\right)+C\).
  5. \(\frac{3}{2} \left(\sqrt[3]{x^2} -2\sqrt[3]{x} +2 \ln \left(\sqrt[3]{x}+1\right)\right)+C\).
  6. \(- x^2 -9 x-27 \ln |x-3| +C\).
  7. \(\frac{1}{2}(\sin 2x + \cos 2x)+C\).
  8. \(-\frac{4}{5}\sqrt{1+\sqrt{x}}\left (x-3\sqrt{x}+6\right )+C.\)

5.5.6

  1. \(\arcsin \frac{x}{2}+C\).
  2. \(\frac{1}{4} \arctan 2 x+C\).
  3. \(\frac{\sqrt{2}}{2}\text{arcsec}\frac{x}{\sqrt{2}}+C\).
  4. \(\frac{1}{\sqrt{6}}\arctan \frac{\sqrt{2}x}{\sqrt{3}} +C\).
  5. \(\arctan (x+3)+C\).
  6. \(\arcsin \frac{x-3}{2}+C\).
  7. \(\frac{1}{\sqrt{2}}\arcsin \frac{\sqrt{2}}{\sqrt{7}}
    (x-1)+C\).
  8. \(\frac{1}{3}\text{arcsec}\frac{x+3}{3}+C\)
  9. \(\frac{1}{2}\left (\ln(x^2+4 x+6)-\sqrt{2}\arctan\frac{x+2}{\sqrt{2}}\right )+C\).
  10. Use Theorem 1 in 5.1.1.