Section 6.6

Please post comments if you find any errors, or if you wish to contribute answers for additional problems. You may find information on using \LaTeX here.

1. (a) \displaystyle{\int \frac{3}{\sqrt{16-x^2}} \ dx = 3\sin^{-1}\left(\frac{x}{4}\right) + c}

(c) \displaystyle{\int \sqrt{5-z^2} \ dz = \frac{z}{2}\sqrt{5-z^2} + \frac{5}{2}\sin^{-1}\left(\frac{z}{\sqrt{5}}\right) + c}

(e) \displaystyle{\int \frac{1}{\sqrt{4+x^2}} \ dx = \log\left|\sqrt{4+x^2} + x\right| + c}

2. (a) \displaystyle{\int z\sqrt{1-z^2} \ dz = -\frac{1}{3}(1 - z^2)^{\frac{3}{2}} + c}

(c) \displaystyle{\int \frac{1}{\sqrt{x^2 - 4}} \ dx = \log\left|x + \sqrt{x^2-4}\right| + c}

(e) \displaystyle{\int \frac{4}{\sqrt{3-2x^2}}  \ dx = 2\sqrt{2}\sin^{-1}\left(\sqrt{\frac{2}{3}}x\right) + c}

(g) \displaystyle{\int \sqrt{4-t^2} \ dt = \frac{t}{2}\sqrt{4-t^2} + 2\sin^{-1}\left(\frac{t}{2}\right)}

3. (a) \displaystyle{\int_0^3 \sqrt{9-t^2} \ dt = \frac{9\pi}{4}}

(c) \displaystyle{\int_0^1 \frac{1}{(1+x^2)^{\frac{3}{2}}} \ dx = \frac{1}{\sqrt{2}}}

(e) \displaystyle{\int_{5\sqrt{2}}^{10} \frac{1}{\sqrt{x^2-25}} \ dx = \log(2+\sqrt{3}) - \log(1 + \sqrt{2})}

5. \displaystyle{\int \frac{1}{\sqrt{1-x^2}} \ dx = -\cos^{-1}(x) + c}

3 Responses to “Section 6.6”

  1. Juan Manuel Barreneche Says:

    The answer for 1.e it’s wrong: me and wolfram’s integrator (http://integrals.wolfram.com/index.jsp) agree that the solution is

    log|sqrt(x² + 4)/2 + x/2| + C

    thank you,

    JM

    PD: The book it’s great.

  2. Juan Manuel Barreneche Says:

    sorry, i was wrong,

    log|sqrt(x² + 4)/2 + x/2| + C
    = log(|sqrt(x² + 4) + x|/2) + C
    = log|sqrt(x² + 4) + x| - log(2) + C
    = log|sqrt(x² + 4) + x| + C1
    were C1 = C - log(2)

    JM

  3. cssp Says:

    That’s right. Integrals can be tricky that way.

    Dan Sloughter

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