Question

http://prntscr.com/9myc61

Answer 1

This is a pretty involved question!
You might want to start with the essentials. That means you'll need to review "Riemann sum," figure out how to calculate the areas of the rectangles under and over the graph from their heights (according to the graph) and widths (which is what?), sum up these areas. First do the Riemann sum for left interval end points, then do the same for right interval endpoints. Once you've finished this, it should be easier to visualize what you're comparing.