# Riemann Sums and Integrals

• Aug 29th 2009, 08:35 AM
Billy Maize
Riemann Sums and Integrals
Question: Find the integral of the equation 2x+1 from 0 to 3 using Riemann Sums.

Please show me how to do this, I keep on getting 9 as the answer, but it is actually 12. (Worried)
• Aug 29th 2009, 08:52 AM
eXist
It depends on the Riemann Sum that you use. Either right, left or center. Also it depends on how many intervals you split it up into. Are there anymore instructions to the problem?
• Aug 29th 2009, 08:55 AM
Billy Maize
I am using right Reimann sums and I am using infinite intervals n->∞.
• Aug 29th 2009, 09:01 AM
eXist
Then that's the same as the actual integral if $n \Rightarrow \infty$. Cause that means that $dx \Rightarrow 0$.

So, take the actuall integral and you get:

$\int_0^3 2x + 1\, dx = x^2 + x$ between 0 and 3.

$= 3^2 + 3 - (0^2 + 0)$
• Aug 29th 2009, 09:04 AM
Billy Maize
ok thnks!