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Math Help - definite integral

  1. #1
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    definite integral

    I have two problems the first, x^9dx from 2b to b and I got x^10/10 so I put it in the calculator and it gave me an answer of 11215267.66 but the back of the book has a different answer. The other one is dx/sqrt(1-x^2) from 0.7 to 0 and I got -d*sqrt(1-x^2) and I also put this in the calculator and it gave me -.49989999. I did about fifteen other problems and they all came out can you tell me where I went wrong.
    Thank You,
    Keith
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by keith View Post
    I have two problems the first, x^9dx from 2b to b and I got x^10/10 so I put it in the calculator and it gave me an answer of 11215267.66 but the back of the book has a different answer. The other one is dx/sqrt(1-x^2) from 0.7 to 0 and I got -d*sqrt(1-x^2) and I also put this in the calculator and it gave me -.49989999. I did about fifteen other problems and they all came out can you tell me where I went wrong.
    Thank You,
    Keith
    how did you manage to get a numerical answer? what is b?

    the formula for your first integral is correct, the second is not
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  3. #3
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    Quote Originally Posted by keith View Post
    The other one is dx/sqrt(1-x^2) from 0.7 to 0 and I got -d*sqrt(1-x^2) and I also put this in the calculator and it gave me -.49989999.
    Actually

    \int\frac1{\sqrt{1-x^2}}\,dx=\arcsin x+k

    For the first one... b<0 or b>0?
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