How to find an integer solution?












2












$begingroup$


Given:



3*(c^3 - c^2*b - c*a^2 + a^2*b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - 3 a b c


Need to solve for all three variables as integers. Problem is to find one solution where all variables are positive.










share|improve this question











$endgroup$












  • $begingroup$
    please review my edit. Some of your formatting of the formula made it unclear and I'm not sure that I got it completely right.
    $endgroup$
    – Carl Lange
    Jan 27 at 9:56








  • 1




    $begingroup$
    @carl lange Gostei muito do seu canal no YouTube
    $endgroup$
    – LCarvalho
    Jan 27 at 11:19










  • $begingroup$
    @LCarvalho Obrigado pelas suas palavras gentis!!
    $endgroup$
    – Carl Lange
    Jan 27 at 15:14
















2












$begingroup$


Given:



3*(c^3 - c^2*b - c*a^2 + a^2*b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - 3 a b c


Need to solve for all three variables as integers. Problem is to find one solution where all variables are positive.










share|improve this question











$endgroup$












  • $begingroup$
    please review my edit. Some of your formatting of the formula made it unclear and I'm not sure that I got it completely right.
    $endgroup$
    – Carl Lange
    Jan 27 at 9:56








  • 1




    $begingroup$
    @carl lange Gostei muito do seu canal no YouTube
    $endgroup$
    – LCarvalho
    Jan 27 at 11:19










  • $begingroup$
    @LCarvalho Obrigado pelas suas palavras gentis!!
    $endgroup$
    – Carl Lange
    Jan 27 at 15:14














2












2








2





$begingroup$


Given:



3*(c^3 - c^2*b - c*a^2 + a^2*b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - 3 a b c


Need to solve for all three variables as integers. Problem is to find one solution where all variables are positive.










share|improve this question











$endgroup$




Given:



3*(c^3 - c^2*b - c*a^2 + a^2*b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - 3 a b c


Need to solve for all three variables as integers. Problem is to find one solution where all variables are positive.







equation-solving






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Jan 27 at 14:09







Dale

















asked Jan 27 at 9:39









DaleDale

1305




1305












  • $begingroup$
    please review my edit. Some of your formatting of the formula made it unclear and I'm not sure that I got it completely right.
    $endgroup$
    – Carl Lange
    Jan 27 at 9:56








  • 1




    $begingroup$
    @carl lange Gostei muito do seu canal no YouTube
    $endgroup$
    – LCarvalho
    Jan 27 at 11:19










  • $begingroup$
    @LCarvalho Obrigado pelas suas palavras gentis!!
    $endgroup$
    – Carl Lange
    Jan 27 at 15:14


















  • $begingroup$
    please review my edit. Some of your formatting of the formula made it unclear and I'm not sure that I got it completely right.
    $endgroup$
    – Carl Lange
    Jan 27 at 9:56








  • 1




    $begingroup$
    @carl lange Gostei muito do seu canal no YouTube
    $endgroup$
    – LCarvalho
    Jan 27 at 11:19










  • $begingroup$
    @LCarvalho Obrigado pelas suas palavras gentis!!
    $endgroup$
    – Carl Lange
    Jan 27 at 15:14
















$begingroup$
please review my edit. Some of your formatting of the formula made it unclear and I'm not sure that I got it completely right.
$endgroup$
– Carl Lange
Jan 27 at 9:56






$begingroup$
please review my edit. Some of your formatting of the formula made it unclear and I'm not sure that I got it completely right.
$endgroup$
– Carl Lange
Jan 27 at 9:56






1




1




$begingroup$
@carl lange Gostei muito do seu canal no YouTube
$endgroup$
– LCarvalho
Jan 27 at 11:19




$begingroup$
@carl lange Gostei muito do seu canal no YouTube
$endgroup$
– LCarvalho
Jan 27 at 11:19












$begingroup$
@LCarvalho Obrigado pelas suas palavras gentis!!
$endgroup$
– Carl Lange
Jan 27 at 15:14




$begingroup$
@LCarvalho Obrigado pelas suas palavras gentis!!
$endgroup$
– Carl Lange
Jan 27 at 15:14










1 Answer
1






active

oldest

votes


















7












$begingroup$

Use FindInstance.



f = 3*(c^3 - c^2 b - c a^2 + a^2 b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - (3 a b c)

FindInstance[f, {a, b, c}, Integers, 3]



{{a -> -130, b -> -130, c -> 65}, {a -> -1, b -> 0, c -> 1}, {a -> 1,
b -> 0, c -> -1}}




We can test the solutions out:



f /. {a -> -130, b -> -130, c -> 65}



True







share|improve this answer









$endgroup$













  • $begingroup$
    Nice work! Do you think it would be possible to have all variables positive? I meant to add this to the question/will edit.
    $endgroup$
    – Dale
    Jan 27 at 14:08










  • $begingroup$
    Found this: mathematica.stackexchange.com/questions/74215/…
    $endgroup$
    – Dale
    Jan 27 at 14:14








  • 1




    $begingroup$
    @Dale Yes, simply add the extra constraints to the first argument in FindInstance: FindInstance[{f, a > 0, b > 0, c > 0}, {a, b, c}, Integers, 1] However, in this case it does not appear that a solution exists.
    $endgroup$
    – Carl Lange
    Jan 27 at 15:13













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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









7












$begingroup$

Use FindInstance.



f = 3*(c^3 - c^2 b - c a^2 + a^2 b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - (3 a b c)

FindInstance[f, {a, b, c}, Integers, 3]



{{a -> -130, b -> -130, c -> 65}, {a -> -1, b -> 0, c -> 1}, {a -> 1,
b -> 0, c -> -1}}




We can test the solutions out:



f /. {a -> -130, b -> -130, c -> 65}



True







share|improve this answer









$endgroup$













  • $begingroup$
    Nice work! Do you think it would be possible to have all variables positive? I meant to add this to the question/will edit.
    $endgroup$
    – Dale
    Jan 27 at 14:08










  • $begingroup$
    Found this: mathematica.stackexchange.com/questions/74215/…
    $endgroup$
    – Dale
    Jan 27 at 14:14








  • 1




    $begingroup$
    @Dale Yes, simply add the extra constraints to the first argument in FindInstance: FindInstance[{f, a > 0, b > 0, c > 0}, {a, b, c}, Integers, 1] However, in this case it does not appear that a solution exists.
    $endgroup$
    – Carl Lange
    Jan 27 at 15:13


















7












$begingroup$

Use FindInstance.



f = 3*(c^3 - c^2 b - c a^2 + a^2 b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - (3 a b c)

FindInstance[f, {a, b, c}, Integers, 3]



{{a -> -130, b -> -130, c -> 65}, {a -> -1, b -> 0, c -> 1}, {a -> 1,
b -> 0, c -> -1}}




We can test the solutions out:



f /. {a -> -130, b -> -130, c -> 65}



True







share|improve this answer









$endgroup$













  • $begingroup$
    Nice work! Do you think it would be possible to have all variables positive? I meant to add this to the question/will edit.
    $endgroup$
    – Dale
    Jan 27 at 14:08










  • $begingroup$
    Found this: mathematica.stackexchange.com/questions/74215/…
    $endgroup$
    – Dale
    Jan 27 at 14:14








  • 1




    $begingroup$
    @Dale Yes, simply add the extra constraints to the first argument in FindInstance: FindInstance[{f, a > 0, b > 0, c > 0}, {a, b, c}, Integers, 1] However, in this case it does not appear that a solution exists.
    $endgroup$
    – Carl Lange
    Jan 27 at 15:13
















7












7








7





$begingroup$

Use FindInstance.



f = 3*(c^3 - c^2 b - c a^2 + a^2 b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - (3 a b c)

FindInstance[f, {a, b, c}, Integers, 3]



{{a -> -130, b -> -130, c -> 65}, {a -> -1, b -> 0, c -> 1}, {a -> 1,
b -> 0, c -> -1}}




We can test the solutions out:



f /. {a -> -130, b -> -130, c -> 65}



True







share|improve this answer









$endgroup$



Use FindInstance.



f = 3*(c^3 - c^2 b - c a^2 + a^2 b) == 
a^3 + b^3 + c^3 + 3*(a + b + c)*(a b + a c + b c) - (3 a b c)

FindInstance[f, {a, b, c}, Integers, 3]



{{a -> -130, b -> -130, c -> 65}, {a -> -1, b -> 0, c -> 1}, {a -> 1,
b -> 0, c -> -1}}




We can test the solutions out:



f /. {a -> -130, b -> -130, c -> 65}



True








share|improve this answer












share|improve this answer



share|improve this answer










answered Jan 27 at 10:03









Carl LangeCarl Lange

5,02711141




5,02711141












  • $begingroup$
    Nice work! Do you think it would be possible to have all variables positive? I meant to add this to the question/will edit.
    $endgroup$
    – Dale
    Jan 27 at 14:08










  • $begingroup$
    Found this: mathematica.stackexchange.com/questions/74215/…
    $endgroup$
    – Dale
    Jan 27 at 14:14








  • 1




    $begingroup$
    @Dale Yes, simply add the extra constraints to the first argument in FindInstance: FindInstance[{f, a > 0, b > 0, c > 0}, {a, b, c}, Integers, 1] However, in this case it does not appear that a solution exists.
    $endgroup$
    – Carl Lange
    Jan 27 at 15:13




















  • $begingroup$
    Nice work! Do you think it would be possible to have all variables positive? I meant to add this to the question/will edit.
    $endgroup$
    – Dale
    Jan 27 at 14:08










  • $begingroup$
    Found this: mathematica.stackexchange.com/questions/74215/…
    $endgroup$
    – Dale
    Jan 27 at 14:14








  • 1




    $begingroup$
    @Dale Yes, simply add the extra constraints to the first argument in FindInstance: FindInstance[{f, a > 0, b > 0, c > 0}, {a, b, c}, Integers, 1] However, in this case it does not appear that a solution exists.
    $endgroup$
    – Carl Lange
    Jan 27 at 15:13


















$begingroup$
Nice work! Do you think it would be possible to have all variables positive? I meant to add this to the question/will edit.
$endgroup$
– Dale
Jan 27 at 14:08




$begingroup$
Nice work! Do you think it would be possible to have all variables positive? I meant to add this to the question/will edit.
$endgroup$
– Dale
Jan 27 at 14:08












$begingroup$
Found this: mathematica.stackexchange.com/questions/74215/…
$endgroup$
– Dale
Jan 27 at 14:14






$begingroup$
Found this: mathematica.stackexchange.com/questions/74215/…
$endgroup$
– Dale
Jan 27 at 14:14






1




1




$begingroup$
@Dale Yes, simply add the extra constraints to the first argument in FindInstance: FindInstance[{f, a > 0, b > 0, c > 0}, {a, b, c}, Integers, 1] However, in this case it does not appear that a solution exists.
$endgroup$
– Carl Lange
Jan 27 at 15:13






$begingroup$
@Dale Yes, simply add the extra constraints to the first argument in FindInstance: FindInstance[{f, a > 0, b > 0, c > 0}, {a, b, c}, Integers, 1] However, in this case it does not appear that a solution exists.
$endgroup$
– Carl Lange
Jan 27 at 15:13




















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