QUESTION:

I know of the more understanding formula for the trapezoidal rule. However, I came across this new form in a book i'm reading. Can someone tell me how I'm suppose to enter the respected values into this new form. Really would like to understand what is going on.

![enter image description here](https://i.stack.imgur.com/daZ4D.png)

I'm assuming that the first part (b-a)/n will come to 1 so we can disregard it. 

Next I'm assuming that [f(a) + f(b)]/2 will be set up like (f(-2)+f(5))/2 which is about 3.667544

The summation part is confusing and I'm not even for sure if i'm correct above. I'm coming out with an answer around 13.334698. Which it should be around 17.017422. Any guidance is appreciated.