Spot The Flaw

Many of you must have seen numerous examples of such situations where we get an absurd result and have to spot flaw in proof.

A famous one is the “algebraic proof of 1=0”

Here I came across a “Calculus based proof of 1=0” in A Mathematical Mosaic which I wanted to share with you.

It is based on “Integration by Parts” formula, which is:

So, the proof is of this form:

Hello World

Here is my first post.

I was just reading “Through the Mathscope by C. Stanley Ogilvy” there he points out a flaw in rigorous proof by Euclid in his Elements, see if you can point out the flaw in following problem (by Euclid).