Question

need help on the attachment problem @Calculus1

Answer 1

if you divide it in 6 equal parts then each part has a width of 1 which makes calculating area by rectangles quite simple

Answer 2

you need to estimate or pull out the values that are at the left most parts; or simply:

f(-3,-2,-1,0,1,2) and add them up

Answer 3

they was nice enough to give you the curve to hit the integers at those points :)