Solving Sum HW Trouble: b-a=2, n=4, delta x=1/2

[Qube]

Homework Statement

I'm having trouble writing a sum for this:

https://scontent-b-mia.xx.fbcdn.net/hphotos-frc3/v/1420232_10201136345792485_382911431_n.jpg?oh=ebd9432103184956c863370121e326ce&oe=529332ED

Homework Equations

delta x = (b-a)/n

n = 4
b-a = 2
delta x = 1/2

The Attempt at a Solution

I keep writing this. But we can't solve this for anything; 4/i when i = 0 is infinity. What am I doing wrong?

https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-prn1/v/536211_10201136357192770_1062632899_n.jpg?oh=c155bbe6c53633a848621aacfcffc055&oe=52931A0F&__gda__=1385430375_4a3d5c0ebb07b3aaff69a8869b9a8da5

 

[SteamKing]

For one thing, f(x) = 2/x. IDK what 4/i is supposed to represent.

 

[Qube]

I think the issue here is finding the correct general term for x_i and the correct bounds of summation.

I did it again, and this time for the general term I am using i/2 + 1, and the bounds of summation as i = 0 and i = 3.

I find that drawing a sketch helps. Immensely.

https://scontent-b-mia.xx.fbcdn.net/hphotos-prn2/v/1469817_10201136445594980_301054541_n.jpg?oh=0d3937e4a716935b821122e27ba1781d&oe=5292C107