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Cubic Diophantine (Posted on 2024-04-18) Difficulty: 3 of 5
Find six distinct positive integers A, B, C, D, E, F, G satisfying:
 A3 + B3 = C3 + D3 = E3 + F3 = 19G3.
Please submit primitive solutions only, that is, A, B, C, D, E, F, G should not have a common factor.

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution computer solution | Comment 1 of 2
clearvars,clc
values=double.empty(0,3);
for a=1:4000
  for b=1:4000
    if b>a
      g3=(a^3+b^3)/19;
      if g3==floor(g3)
        g=round(g3^(1/3));
        if g^3==g3
          values(end+1,:)=[a,b,g];
        end
      end
    end
  end
end
v=sortrows(values,3);
for i=1:length(v)-2
  if v(i,3)==v(i+1,3) && v(i,3)==v(i+2,3)
    disp(v(i,:))
    disp(v(i+1,:))
    disp(v(i+2,:))
    disp(' ')
  end
end

finds answers that are all multiples of the sought solution shown here:

                      G

A, B:   70   560     210
C, D:  198   552     210
E, F:  315   525     210

Of course A and B can be interchanged, etc. and the pairs themselves can be permuted, so long as 70 is still paired with 560, etc.

The cubes of the members of the pairs are

      343000   175616000
     7762392   168196608
    31255875   144703125
    
and

 19*G^3 =  175959000

  Posted by Charlie on 2024-04-18 08:57:42
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