Integrals Problem

Question

Estimate the area under the graph of f(x)=(x^2)+3x from x=5 to x=8 using 3 approximating rectangles and left endpoints.

Approximation =

Answer 1

You subdivide the interval in 3: x0 = 5, x1=6, x2=7, and x3=8

The sum of the areas of the rectangles using the LHS value for f(x):

(f(x0) + f(x1) + f(x2)) Δx (here all delta x are equal to 1)

So, in this case, the integral is approximated by f(5) + f(6) + f(7)

Good luck!