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Math Help - just hints in integrals

  1. #1
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    Post just hints in integrals

    • Im in the middle of solving an integration and just need to know what is
    16 cos^2 x in terms of sec^2 x
    • what is the integral of cosx/sin^2 x
    • integral of x^2/(x^2 +1)

    thank you
    appreciate any help
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  2. #2
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    1. \sec{x} = \frac{1}{\cos{x}}

    2. You can try u = \sin{x}, or maybe it would be more clear if you see it as \csc{x}\cot{x}.

    3. Simply add 0 using 1. This is a basically a quick way around long division:
    \frac{x^2+1-1}{x^2+1} = \frac{x^2+1}{x^2+1} - \frac{1}{x^2+1} = \ldots
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  3. #3
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    Question Chop Suey

    Thank you for replying.
    the problem is
    1- the integral is (sec^2 x +8secx cosx +16cos^x dx) so i was trying to find the relation or form of 16cos^2x in terms of the sec^2 x)

    2-the integral of this question was (1/(sin^2x) - cosx/sin^2x )

    3- i got the same result: integral 1+ 1/(x^2+1)
    so im looking for the integral of 1/(x^+1)

    THANK YOU AGAIN
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  4. #4
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    Quote Originally Posted by alex83 View Post
    Thank you for replying.
    the problem is
    1- the integral is (sec^2 x +8secx cosx +16cos^x dx) so i was trying to find the relation or form of 16cos^2x in terms of the sec^2 x)

    2-the integral of this question was (1/(sin^2x) - cosx/sin^2x )

    3- i got the same result: integral 1+ 1/(x^2+1)
    so im looking for the integral of 1/(x^+1)

    THANK YOU AGAIN
    Maths is not a spectator sport. Review the methods you have been taught. What have you tried? Where do you get stuck? You should realise that \int \frac{1}{x^2 + 1} \, dx is a standard form.
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