/sci/ - Science & Math » Thread #13221959

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Prove that 7 is the only prime that is followed by a cube. Now.

Anonymous Tue 01 Jun 17:13:00 2021 No.13221959 View Reply Original Report

Quoted By: >>13222038

Anonymous

Anonymous Tue 01 Jun 2021 17:13:52 No.13221963 Report

Quoted By:

00101011001110010001010010100101000101010111001010100101

Anonymous

Anonymous Tue 01 Jun 2021 17:24:35 No.13222006 Report

Quoted By: >>13222040

ez
p - prime
p+1=x^3 => p=x^3-1
p=(x-1)(x^2+x+1)
p is a prime so we have the following:
x-1=1 => x=2 => p=7
x-1=-1 => x=0 => p=-1, false
x^2+x+1=-1, impossible
x^2+x+1=1 => x=0 or x=-1 => p=-1 or p=-2, false
therefore p=7 is unique

QED

Anonymous

Anonymous Tue 01 Jun 2021 17:32:06 No.13222038 Report

Quoted By:

>>13221959
P=8x+7
for P>7
P=64y+63
that's about all I got

Anonymous

Anonymous Tue 01 Jun 2021 17:33:08 No.13222040 Report

Quoted By:

>>13222006
I'm retarded

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