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Floor on an Exponential Integral (Posted on 2025-03-12) Difficulty: 3 of 5
Evaluate the integral

2
∫ Floor(e^x) dx
0

No Solution Yet Submitted by Brian Smith    
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same; and a picture | Comment 3 of 5 |
[addendum:  the solution below is incorrect, there is also a 7th block which makes the total come out the same as what Charlie and Jer found.  I made this error because I was looking at the graph and it "looked" like 6 blocks was enough.  Thanks to Jer for finding the error.]

Divide region under the curve into blocks.  Could do this as separate definite integrals with vertical dividing lines between blocks.

Or imagine horizontally divided blocks; the dividing lines' left endpoints are on the curve y=e^x.  The right endpoints are at x=2.

The height of each block is 1 unit
Blk# Width
1        2
2     2-ln(2)
3     2-ln(3)
4     2-ln(4)
5     2-ln(5)
6     2-ln(6)

The area is the sum of the 6 widths.
Area = 12 - Σ ln(i) for i = 2 to 6

≈ 5.420748787989899

https://www.desmos.com/calculator/oxjsnprobk

Edited on March 14, 2025, 10:22 am
  Posted by Larry on 2025-03-12 14:46:21

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