Estimate the area under the graph of f(x) =x^2 + 4x from x=1 to x=9 using 4 approximating rectangles and left endpoints.(adsbygoogle = window.adsbygoogle || []).push({});

first i had to find delta x, so i did 9-1/4 = 2

which means x0 = 0, x1 = 2, x2= 4, x3=6 (since i'm using left endpoints, i include x0)

after that, i just plug it in the left end point formula:

L4 = 2*0 + 2*12 + 2*32 + 2*60 = 208

i done the calculations many time and get the same answer, am i missing something?

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