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Math Help - f(x), a & b values from Riemann Sum

  1. #1
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    f(x), a & b values from Riemann Sum

    Hi everyone,

    I'm very confused about how to do this problem, could someone please explain this to me?

    Thank you

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  2. #2
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    What you're being asked to do is to look at this Riemann sum & look for patterns.

    It says to use A = 0 so we have some information already, you'll see how helpful that is in a second.

    What we know so far:

    \int_{a} f (x)\,dx

    Okay, what is the definition of a Riemann sum?

    \lim_{x \to \infty}  \sum_{i=1}^{n} f(x_i) \Delta x

    where;

    \Delta x = \frac{b - a}{n} \ and \ x_i = a + i\Delta x

    I could do the rest but I'll let you read this and see if you can figure the rest out on your own, if not I'll help you some more
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  3. #3
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    Great, I think that helped. So it's:

    f(x) = (8+x)^(1/2)
    a=0
    b=5
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  4. #4
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    Yep
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  5. #5
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    Thank you!

    I hate to be a bother, but do you have any suggestions for this one?


    Sorry, I guess I was just being impatient

    f(x) = tan (x/4)
    a = 0
    b = pi/6

    Thanks again for the help!
    Last edited by theshrink; May 4th 2010 at 05:46 PM. Reason: I figured it out
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  6. #6
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    yeah, think about trigonometric limits. They are never like a = 2, b = 5, they are more like;

    \int_{\frac{\pi}{9}}^{\frac{7\pi}{6}} f (x)\,dx


    I'll give you a hint, you can take a = 0 in this one too & follow the same procedure, any problems just post back.

    edit: no problem
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  7. #7
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    I must have edited while you looked at it, but i figured it out! Thank you!
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