# Riemann sums

• February 4th 2009, 10:01 AM
fattydq
Riemann sums
I'm having trouble understanding how to express integrals as the limit of Riemann sums and visa versa. I've attached a picture with the current problem I'm working on if someone wouldn't mind helping me I'd really appreciate it. You can see my current (incorrect) response to the question to get an idea of what I was TRYING to do.
• February 4th 2009, 10:14 AM
Plato
It is a simple mistake: the 1 should be a 3 as in $3+\frac{4i}{n}$
• February 4th 2009, 10:18 AM
Krizalid
I think all you need is to check your image:

http://img516.imageshack.us/img516/4711/sdfsdfnv7.png
http://img516.imageshack.us/img516/s...png/1/w562.png

So take $\Delta x=\frac{4}{n}$ so that ${{x}_{i}}=3+\frac{4i}{n},$ so

$\int_{3}^{7}{\frac{x}{2+{{x}^{5}}}\,dx}=\underset{ n\to \infty }{\mathop{\lim }}\,\frac{4}{n}\sum\limits_{i=1}^{n}{\frac{3+\dfra c{4i}{n}}{2+{{\left( 3+\dfrac{4i}{n} \right)}^{5}}}}.$

-- Ahhh, Plato beat me to it.
• February 4th 2009, 10:22 AM
fattydq
So it should be a 3 instead of a 1 because the a is 3 and not 1, correct? Just making sure I understand
• February 4th 2009, 10:26 AM
fattydq
Never mind this response, wrong thread, lol