# Riemann sum question

• September 30th 2007, 08:11 AM
jst706
Riemann sum question
http://i231.photobucket.com/albums/e...13/newmath.jpg
It says the answer is 32? How do I go about solving this thing? Thanks
• September 30th 2007, 10:00 AM
Jhevon
Quote:

Originally Posted by jst706
http://i231.photobucket.com/albums/e...13/newmath.jpg
It says the answer is 32? How do I go about solving this thing? Thanks

do you recall the definition of a finite Riemann sum?

Let the endpoints be $a = 1$ and $b = 1$, and $n = 2$ be the number of subintervals.

then $\Delta x = \frac {b - a}{n} = \frac {5 - 1}2 = 2$

if each subinterval is of equal length, then each will be 2 units long. the midpoints would be at $x = 2$ and $x = 4$

Thus, $R_2 = \sum_{i = 1}^{2}f(x_i) \Delta x = f(2) \Delta x + f(4) \Delta x$

just plug in the values and work them out