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Math Help - [SOLVED] Integration

  1. #1
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    [SOLVED] Integration

    I am integrating by parts. I do not know what let u and v be. I am also stuck on the radical.

    e^{sqre rt} 3s+9 ds

    I want to let u = 3s+9 and v = e^rt x

    can it be done or am i just lost?
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  2. #2
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    \int e^{\sqrt{3s+9}} \, ds<br />

    t = \sqrt{3s+9}

    dt = \frac{3}{2\sqrt{3s+9}} \, ds = \frac{3}{2t} \, ds

    ds = \frac{2t}{3} \, dt

    \int e^t \cdot \frac{2t}{3} \, dt

    \frac{2}{3} \int t \cdot e^t \, dt

    now do parts ... let u = t and dv = e^t \, dt
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  3. #3
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    Why did you solve for ds?
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  4. #4
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    because one cannot integrate a function of t w/respect to s.
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  5. #5
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    Thank You

    Thanks skeeter.
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