Some of you may have seen the video:
It is a proof of the irrationality of eπ by Ron (14years) , presented by 'blackpenredpen' Youtuber.
The proof goes something like this:
We know that e^{iπ}=-1 ("Euler's famous identity").
e^{iπ}=i^2
So, π=\frac{2\ln{i}}{i}
We must prove that eπ is irrational.
Let us assume, on the contrary, that eπ is rational.
eπ=\frac{a}{b} where a and b are rational numbers.
eπ=e\frac{2\ln{i}}{i}=\frac{a}{b}
2eb\ln{i}=ai
\ln{i^{2eb}}=ai
\ln{(-1)^{eb}}=ai
(-1)^{eb}=e^{ai}
Squaring on both sides,
1^{eb}=e^{2ai}
1=e^{2ai}
e^0=e^{2ai}
When the bases are identical, the powers are equal.
0=2ai
a=0
Hence,
eπ=\frac{0}{b}
eπ=0
This is not possible and therefore gives us a contradiction.
This contradiction has arisen because of our incorrect assumption the eπ is rational.
We conclude that eπ is irrational.
(*) Is this proof legitimate? Or is there something dubious about it? If so, please point it out.
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