using 5 rectangles what is the area under a curve using the function f(x)=3x+4 with boundries at [0,2]

Answer 1

Assuming equal subintervals, the width of each is 0.4

Using left endpoints, the heights are

4,5.2,6.4,...

Now just add up the areas of the rectangles

Answer 2

A nice online calculator for this can be found at

http://mathworld.wolfram.com/RiemannSum.html