How many non-trivial solutions are there to the equation
a 2 + b 2 = c n
for { a , b , c , n ∈ Z ∣ a , b , c = 0 } , and any n ≥ 3 ?
Bonus: Can you find a general formula?
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
One infinite family of solutions is ( a , b , c , n ) = ( 2 m , 2 m , 2 , 2 m + 1 ) for any integer m ≥ 1 .
If we define integers a k , n , b k , n by setting a k , n + i b k , n = ( 2 + i ) k n then a k , n 2 + b k , n 2 = ∣ ∣ ( 2 + i ) 2 k n ∣ ∣ = 5 k n and so ( a k , n , b k , n , 5 k , n ) is a solution for any integers k ≥ 1 and n ≥ 3 . Thus we get infinitely many solutions for each value of n ≥ 3 .
There are infinitely many integer solutions for a 2 + b 2 = c n , for any integer n ≥ 2 and { a , b , c ∈ Z ∣ a , b , c = 0 } .
Note that I am not certain of the validity of this particular proof/formula. I will be grateful for any suggestions.
Consider any Gaussian integer z . Perform the operation z n , and recall that ∣ z n ∣ 2 = R e ( z n ) 2 + I m ( z n ) 2 , where R e ( z n ) and I m ( z n ) are respectively the real and imaginary coefficients of z n . Now, the complex norm has a nice multiplicative property: ∣ z n ∣ = ∣ z ∣ 2 n because ∣ z n ∣ = ( R e ( z n ) 2 + I m ( z n ) 2 ) n = ( R e ( z n ) 2 + I m ( z n ) 2 ) 2 n = ( R e ( z n ) 2 + I m ( z n ) 2 ) n = ∣ z ∣ n Substituting into the first equation, we obtain ∣ z ∣ n = R e ( z n ) 2 + I m ( z n ) 2 . As R e ( z n ) , I m ( z n ) , and ∣ z ∣ are all positive integers, we have our proof.
Question: Does this formula include all possible integer solutions? What is the distribution of the solution amongst the integers?
An infinite family of solutions for a 2 + b 2 = c 4 is
a = p 4 − 6 p 2 q 2 + q 4
b = 4 p 3 q − 4 p q 3
c = p 2 + q 2
for any integer p and q .
2^2 + 2^2 = 2^3
4^2 + 4^2 = 2^5
8^2 + 8^2 = 2^7
(2^x)^2 + (2^x)^2 = 2^(2x+1)
Problem Loading...
Note Loading...
Set Loading...
Consider a primitive pythagorean triple ( a , b , c ) such that
a 2 + b 2 multiplying throughout by c 2 n we get, ( a c n ) 2 + ( b c n ) 2 p 2 + q 2 where p = a c n , q = b c n and r = c 2 = c 2 = ( c 2 ) n + 1 = r n + 1 since there are infinitely many Pythagorean triples and each one corresponds to a solution as shown above, there will be infinitely many solutions for each n.