A Framework For Fermat's Marvellous Proof

Pythagorean triples are integer solutions to the equation:

a2+b2=c2

If u and v are positive integers, with v>u and a=v2-u2, b=2uv, and c=v2+u2 provides integer solutions to a2+b2=c2

It is easily possible to demonstrate that this solution can be generalized in the following manner.

a2+b2=c2 can be rewritten as:

b2=c2-a2

and further to

b2=(c+a)(c-a)

Consider then integer solutions to the more general equation (where n is a positive integer):

bn=(c+a)n-1(c-a)

If u and v are positive integers, with v>u and b=2uvn-1, c=vn+un, and a=vn-un provides integer solutions to bn=(c+a)n-1(c-a)

Proof:

bn=(c+a)n-1(c-a)
(2uvn-1)n=((vn+un)+(vn-un))n-1((vn+un)-(vn-un))
2nunvn2-n=(2vn)n-1(2un)
2nunvn2-n=2n-1vn2-n2nun
2nunvn2-n=2nunvn2-n


The more general equation, bn=(c+a)(c-a)n-1, can also be demonstrated in a similar manner if the conditions are the same as above except that b=2un-1v.

Now, Fermat's Last Theorem can be written as:

bn=cn-an

and further to

bn=(a0cn-1+acn-2...+an-2c+an-1c0)(c-a)

For all n > 2, cn-1 and an-1, for any combination of v and u, will produce non-cancellable intermediate terms and, thus, no integer solutions for this form.

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