Question

Estimate the area under the graph of f(x)= x^2 + 2 x from x=1 to x=5 using 4 approximating rectangles and left endpoints.

Answer 1

I assume you want the rectangles to have equal widths. Tat would be (5-1)/4 = 1.

So, the left sides of the rectangles are at x = 1,2,3,4

the heights are f(1),f(2),f(3),f(4).

So, evaluate f there and add up the areas.

Answer 2

I got 50 and it's correct. Thank you. I didn't know how to find the 4 approximate values