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integral help! can you solve this integral?

i am not sure how to solve this integral:

17*[(cos^5(x))/(sqrt(sin(x))]dx

help much appreciated!!

3 Answers

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  • 1 decade ago
    Favorite Answer

    ∫ 17 [ cos^5(x) dx / √(sin x)

    = ∫ 17 [ cos^4(x) ( cos x dx) / √(sin x)

    = 17 ∫ [1 - sin^2(x) ]^2 ( cos x dx) / √(sin x)

    let sin x = u

    cos x dx = du

    now the integral becomes

    17 ∫ [1 - u^2) ]^2 du / √u

    = 17 ∫ [1 + u^4 - 2u^2 ] du / √u

    = 17 ∫(u)^(- 1/2) du + 17 ∫ u^(7/2) du - 34 ∫ u^(3/2) du

    = 17 * 2√u + 17(2/9) (u)^(9/2) - 34 (2/5) u^(5/2) + c

    = 34√u + (34/9) (u)^(9/2) - (68 / 5) u^(5/2) + c

    back substitute u = sin x

    34√sin x + (34/9) (sin x)^(9/2) - (68 / 5) (sin x) ^(5/2) + C

  • efqy
    Lv 7
    1 decade ago

    You don't "solve" integrals. You solve equations. You evaluate integrals.

    i) Try writing cos^5(x) as cos(x) (1-sin^2(x)]^2. and try u = sin(x)

    ii) similar, but try u = sqrt(sin(x)) instead (if the first doesn't get you there)

  • chente
    Lv 6
    1 decade ago

    lucky

    you are missing a delimiter

    17/180sin(x)^(1/2)(52cos(2x) + 5cos(4x) + 303)

    chente

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