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Math Help - u-substitution check answer

  1. #1
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    u-substitution check answer

    problem - integral x^3(sqrt(x^3+1)dx

    u = x^3 +1
    du= 3x^2

    du/3=x^2dx

    so integral u^1/2(du/3) = 1/3 integral u^1/2 du

    1/3 (U^3/2)/(3/2) = 2/9 u^3/2

    2/9(x^3+1)^3/2 + c
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by weezie23 View Post
    problem - integral x^3(sqrt(x^3+1)dx

    u = x^3 +1
    du= 3x^2

    du/3=x^2dx

    so integral u^1/2(du/3) = 1/3 integral u^1/2 du

    1/3 (U^3/2)/(3/2) = 2/9 u^3/2

    2/9(x^3+1)^3/2 + c
    i suppose you meant \int x^2 \sqrt{x^3 + 1}~dx
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  3. #3
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    yes

    yes - how do you post the equasions so clearly with the text?
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by weezie23 View Post
    yes
    well, in that case, you are correct. good job

    how do you post the equasions so clearly with the text?
    I used LaTeX
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