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Math Help - integrals Help please

  1. #1
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    integrals Help please

    e^-2.5xdx .... i got -5/2e^2,5x+c

    Xcosx(3x^2)dx.... i got 1/12sin(3x^2) + c

    (5x/x^2+1)dx

    X(x^2-8)^1/2 dx

    (1-e^-x/e^-x)dx

    (3x-2)^5/2 dx
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  2. #2
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    Quote Originally Posted by BigBlack View Post
    e^-2.5xdx .... i got -5/2e^2,5x+c


    Quote Originally Posted by BigBlack View Post
    Xcosx(3x^2)dx.... i got 1/12sin(3x^2) + c
    I'm guessing you mean: \int x\cos \left(3x^{2}\right) dx

    Check over your work again. The constant in front of your antiderivative is off. Show your work and we'll see if we can sort it out for you.

    Quote Originally Posted by BigBlack View Post
    (5x/x^2+1)dx
    u = x^{2} + 1

    Quote Originally Posted by BigBlack View Post
    X(x^2-8)^1/2 dx
    u = x^{2} - 8

    Quote Originally Posted by BigBlack View Post
    (1-e^-x/e^-x)dx
    Split the fraction: \frac{1-e^{-x}}{e^{-x}} = \frac{1}{e^{-x}} - \frac{e^{-x}}{e^{-x}}

    And simplify.

    Quote Originally Posted by BigBlack View Post
    (3x-2)^5/2 dx
    u = 3x - 2

    It'd be more helpful if you posted your work so we can pinpoint your mistakes.
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  3. #3
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    Sorry I'm new still trying to figure things out. Thanks though
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