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Math Help - Integration

  1. #1
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    Integration

    Here a few questions i had solved by the method that was asked for can someone please check my answers:

    1) find integrate 4x/(x^2+2x+5) dx

    I got 2ln((x+1)^2+4) -2Arctan((x+1)/2) +C

    2) find integrate (2x^3-4x^2-15x+5)/(x^2-2x-8) dx by partial fractions and long division

    I got x^2 +1.5ln(x-4) -0.5ln(x+2) +C

    3) integrate lnx/x dx

    I got 0.5(lnx)^2 +C

    4) integrate cosxln(sinx) dx

    I got sinxln(sinx) -sinx +C

    Any changes are appreciated and yes to ll is even more appreciated
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  2. #2
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    Quote Originally Posted by deragon999 View Post
    Here a few questions i had solved by the method that was asked for can someone please check my answers:

    1) find integrate 4x/(x^2+2x+5) dx

    I got 2ln((x+1)^2+4) -2Arctan((x+1)/2) +C

    2) find integrate (2x^3-4x^2-15x+5)/(x^2-2x-8) dx by partial fractions and long division

    I got x^2 +1.5ln(x-4) -0.5ln(x+2) +C

    3) integrate lnx/x dx

    I got 0.5(lnx)^2 +C

    4) integrate cosxln(sinx) dx

    I got sinxln(sinx) -sinx +C

    Any changes are appreciated and yes to ll is even more appreciated
    These are all correct.

    You do realize you can check your work by taking the derivative of the answer?

    -Dan
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