1. ## integration

Estimate the area under the graph of from to using approximating rectangles and left endpoints

2. Originally Posted by sss
Estimate the area under the graph of from to using approximating rectangles and left endpoints
$\displaystyle \Delta x =\frac{4-1}{3}=1$

so our sample points are 1,2,3

so the area is

$\displaystyle \Delta x(f(1)+f(2)+f(3))=1(5+12+21)=38$