Can $3p^4-3p^2+1$ be square number?
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I know $4p^4+1$ can't be square number, cause $4p^4<4p^4+1<4p^4+4p^2+1$ for all natural number p.
But I don't know the way to prove $3p^4-3p^2+1$ can(not) be square number. Is there a well known way to prove it?
elementary-number-theory diophantine-equations
$endgroup$
add a comment |
$begingroup$
I know $4p^4+1$ can't be square number, cause $4p^4<4p^4+1<4p^4+4p^2+1$ for all natural number p.
But I don't know the way to prove $3p^4-3p^2+1$ can(not) be square number. Is there a well known way to prove it?
elementary-number-theory diophantine-equations
$endgroup$
3
$begingroup$
$p = 1$ is a square number.
$endgroup$
– Toby Mak
Dec 20 '18 at 11:14
5
$begingroup$
PEOPLE, please stop using $p$ for natural number! Usualy it is $n$ for natural and $p$ for prime. I did whole analisys for nothing.
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– Maria Mazur
Dec 20 '18 at 11:33
1
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You must be fun at parties.
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– Lucas Henrique
Dec 20 '18 at 11:47
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@LucasHenrique Who are you reffering to and what does that have with a math?
$endgroup$
– Maria Mazur
Dec 20 '18 at 12:37
add a comment |
$begingroup$
I know $4p^4+1$ can't be square number, cause $4p^4<4p^4+1<4p^4+4p^2+1$ for all natural number p.
But I don't know the way to prove $3p^4-3p^2+1$ can(not) be square number. Is there a well known way to prove it?
elementary-number-theory diophantine-equations
$endgroup$
I know $4p^4+1$ can't be square number, cause $4p^4<4p^4+1<4p^4+4p^2+1$ for all natural number p.
But I don't know the way to prove $3p^4-3p^2+1$ can(not) be square number. Is there a well known way to prove it?
elementary-number-theory diophantine-equations
elementary-number-theory diophantine-equations
edited Dec 20 '18 at 11:33
Maria Mazur
48.2k1260122
48.2k1260122
asked Dec 20 '18 at 11:11
eandpiandieandpiandi
272
272
3
$begingroup$
$p = 1$ is a square number.
$endgroup$
– Toby Mak
Dec 20 '18 at 11:14
5
$begingroup$
PEOPLE, please stop using $p$ for natural number! Usualy it is $n$ for natural and $p$ for prime. I did whole analisys for nothing.
$endgroup$
– Maria Mazur
Dec 20 '18 at 11:33
1
$begingroup$
You must be fun at parties.
$endgroup$
– Lucas Henrique
Dec 20 '18 at 11:47
$begingroup$
@LucasHenrique Who are you reffering to and what does that have with a math?
$endgroup$
– Maria Mazur
Dec 20 '18 at 12:37
add a comment |
3
$begingroup$
$p = 1$ is a square number.
$endgroup$
– Toby Mak
Dec 20 '18 at 11:14
5
$begingroup$
PEOPLE, please stop using $p$ for natural number! Usualy it is $n$ for natural and $p$ for prime. I did whole analisys for nothing.
$endgroup$
– Maria Mazur
Dec 20 '18 at 11:33
1
$begingroup$
You must be fun at parties.
$endgroup$
– Lucas Henrique
Dec 20 '18 at 11:47
$begingroup$
@LucasHenrique Who are you reffering to and what does that have with a math?
$endgroup$
– Maria Mazur
Dec 20 '18 at 12:37
3
3
$begingroup$
$p = 1$ is a square number.
$endgroup$
– Toby Mak
Dec 20 '18 at 11:14
$begingroup$
$p = 1$ is a square number.
$endgroup$
– Toby Mak
Dec 20 '18 at 11:14
5
5
$begingroup$
PEOPLE, please stop using $p$ for natural number! Usualy it is $n$ for natural and $p$ for prime. I did whole analisys for nothing.
$endgroup$
– Maria Mazur
Dec 20 '18 at 11:33
$begingroup$
PEOPLE, please stop using $p$ for natural number! Usualy it is $n$ for natural and $p$ for prime. I did whole analisys for nothing.
$endgroup$
– Maria Mazur
Dec 20 '18 at 11:33
1
1
$begingroup$
You must be fun at parties.
$endgroup$
– Lucas Henrique
Dec 20 '18 at 11:47
$begingroup$
You must be fun at parties.
$endgroup$
– Lucas Henrique
Dec 20 '18 at 11:47
$begingroup$
@LucasHenrique Who are you reffering to and what does that have with a math?
$endgroup$
– Maria Mazur
Dec 20 '18 at 12:37
$begingroup$
@LucasHenrique Who are you reffering to and what does that have with a math?
$endgroup$
– Maria Mazur
Dec 20 '18 at 12:37
add a comment |
3 Answers
3
active
oldest
votes
$begingroup$
Partial solution if $p$ is prime.
Write $$3p^4-3p^2+1=n^2implies 3p^2(p^2-1) = (n-1)(n+1)$$
If $pne 2$ (which is not a solution) then $p^2mid n-1$ or $p^2mid n+1 $
First case: If $p^2mid n-1$ then $n+1mid 3p^2-3$ so $ n-1= p^2k$ and $n+1leq 3p^2-3$.
If $kgeq 3$ then $$3p^2-3geq n+1 >n-1 geq 3p^2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2+1$ so $$2p^2+2mid 3p^2-3 implies 2p^2+2mid 2(3p^2-3)-3(2p^2+2) = -12$$
So $p^2+1mid 6 implies p^2+1in {1,2,3,6}$ which is impssible.
$bullet$ If $k=1$ then $n= p^2+1$ so $$p^2+2mid 3p^2-3 implies p^2+2mid (3p^2-3)-3(p^2+2) =-9 $$
So $p^2+2mid 9 implies p^2+2in {1,3,9}$ which is impossible again.
Second case: If $p^2mid n+1$ then $n-1mid 3p^2-3$ so $ n+1= p^2k$ and $n-1leq 3p^2-3$.
Again, if $kgeq 3$ then $$3p^2-3geq n-1 = n+1-2geq 3p^2-2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2-1$ so $2p^2-2mid 3p^2-3$ which is impossible.
$bullet$ If $k=1$ then $n= p^2-1$ so $$p^2-2mid 3p^2-3 implies p^2-2mid (3p^2-3)-3(p^2-2) =3 $$
So $p^2-2mid 3 implies p^2-2in {-1,1,3}$ which is impossible again.
So the answer is negative if $p$ is prime.
$endgroup$
1
$begingroup$
what if p is a natural number? Isn't there any way to prove it?
$endgroup$
– eandpiandi
Dec 20 '18 at 12:04
add a comment |
$begingroup$
Hint about method:
$3m^2 - 3m + 1 = n^2$ for any n $in$ Natural, for $p^2 = m$.
$$3m^2 - 3m + 1 - n^2 = 0$$
$$implies m = frac {3 +sqrt{12n^2-3}}6$$
$$implies p^2 = frac {3 +sqrt{12n^2-3}}6$$ or
$$implies p^2 = frac {3 -sqrt{12n^2-3}}6$$
Now you can just make logical comments yourself about this is valid for above given constraints or not, and make out a bit about the equation.
$endgroup$
add a comment |
$begingroup$
You can compare it with general formula for Pythagorean triples: $(p^2-k^2)^2+(2pk)^2=(p^2+k^2)^2$, we have: $(p^2-1)^2+p^2(2p^2-1)$, here $k=1$ and second term must be $(2p)^2$, which is not, so second term is not competent with that of general formula and your tri-nomial can not be square.
$endgroup$
add a comment |
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3 Answers
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3 Answers
3
active
oldest
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active
oldest
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active
oldest
votes
$begingroup$
Partial solution if $p$ is prime.
Write $$3p^4-3p^2+1=n^2implies 3p^2(p^2-1) = (n-1)(n+1)$$
If $pne 2$ (which is not a solution) then $p^2mid n-1$ or $p^2mid n+1 $
First case: If $p^2mid n-1$ then $n+1mid 3p^2-3$ so $ n-1= p^2k$ and $n+1leq 3p^2-3$.
If $kgeq 3$ then $$3p^2-3geq n+1 >n-1 geq 3p^2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2+1$ so $$2p^2+2mid 3p^2-3 implies 2p^2+2mid 2(3p^2-3)-3(2p^2+2) = -12$$
So $p^2+1mid 6 implies p^2+1in {1,2,3,6}$ which is impssible.
$bullet$ If $k=1$ then $n= p^2+1$ so $$p^2+2mid 3p^2-3 implies p^2+2mid (3p^2-3)-3(p^2+2) =-9 $$
So $p^2+2mid 9 implies p^2+2in {1,3,9}$ which is impossible again.
Second case: If $p^2mid n+1$ then $n-1mid 3p^2-3$ so $ n+1= p^2k$ and $n-1leq 3p^2-3$.
Again, if $kgeq 3$ then $$3p^2-3geq n-1 = n+1-2geq 3p^2-2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2-1$ so $2p^2-2mid 3p^2-3$ which is impossible.
$bullet$ If $k=1$ then $n= p^2-1$ so $$p^2-2mid 3p^2-3 implies p^2-2mid (3p^2-3)-3(p^2-2) =3 $$
So $p^2-2mid 3 implies p^2-2in {-1,1,3}$ which is impossible again.
So the answer is negative if $p$ is prime.
$endgroup$
1
$begingroup$
what if p is a natural number? Isn't there any way to prove it?
$endgroup$
– eandpiandi
Dec 20 '18 at 12:04
add a comment |
$begingroup$
Partial solution if $p$ is prime.
Write $$3p^4-3p^2+1=n^2implies 3p^2(p^2-1) = (n-1)(n+1)$$
If $pne 2$ (which is not a solution) then $p^2mid n-1$ or $p^2mid n+1 $
First case: If $p^2mid n-1$ then $n+1mid 3p^2-3$ so $ n-1= p^2k$ and $n+1leq 3p^2-3$.
If $kgeq 3$ then $$3p^2-3geq n+1 >n-1 geq 3p^2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2+1$ so $$2p^2+2mid 3p^2-3 implies 2p^2+2mid 2(3p^2-3)-3(2p^2+2) = -12$$
So $p^2+1mid 6 implies p^2+1in {1,2,3,6}$ which is impssible.
$bullet$ If $k=1$ then $n= p^2+1$ so $$p^2+2mid 3p^2-3 implies p^2+2mid (3p^2-3)-3(p^2+2) =-9 $$
So $p^2+2mid 9 implies p^2+2in {1,3,9}$ which is impossible again.
Second case: If $p^2mid n+1$ then $n-1mid 3p^2-3$ so $ n+1= p^2k$ and $n-1leq 3p^2-3$.
Again, if $kgeq 3$ then $$3p^2-3geq n-1 = n+1-2geq 3p^2-2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2-1$ so $2p^2-2mid 3p^2-3$ which is impossible.
$bullet$ If $k=1$ then $n= p^2-1$ so $$p^2-2mid 3p^2-3 implies p^2-2mid (3p^2-3)-3(p^2-2) =3 $$
So $p^2-2mid 3 implies p^2-2in {-1,1,3}$ which is impossible again.
So the answer is negative if $p$ is prime.
$endgroup$
1
$begingroup$
what if p is a natural number? Isn't there any way to prove it?
$endgroup$
– eandpiandi
Dec 20 '18 at 12:04
add a comment |
$begingroup$
Partial solution if $p$ is prime.
Write $$3p^4-3p^2+1=n^2implies 3p^2(p^2-1) = (n-1)(n+1)$$
If $pne 2$ (which is not a solution) then $p^2mid n-1$ or $p^2mid n+1 $
First case: If $p^2mid n-1$ then $n+1mid 3p^2-3$ so $ n-1= p^2k$ and $n+1leq 3p^2-3$.
If $kgeq 3$ then $$3p^2-3geq n+1 >n-1 geq 3p^2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2+1$ so $$2p^2+2mid 3p^2-3 implies 2p^2+2mid 2(3p^2-3)-3(2p^2+2) = -12$$
So $p^2+1mid 6 implies p^2+1in {1,2,3,6}$ which is impssible.
$bullet$ If $k=1$ then $n= p^2+1$ so $$p^2+2mid 3p^2-3 implies p^2+2mid (3p^2-3)-3(p^2+2) =-9 $$
So $p^2+2mid 9 implies p^2+2in {1,3,9}$ which is impossible again.
Second case: If $p^2mid n+1$ then $n-1mid 3p^2-3$ so $ n+1= p^2k$ and $n-1leq 3p^2-3$.
Again, if $kgeq 3$ then $$3p^2-3geq n-1 = n+1-2geq 3p^2-2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2-1$ so $2p^2-2mid 3p^2-3$ which is impossible.
$bullet$ If $k=1$ then $n= p^2-1$ so $$p^2-2mid 3p^2-3 implies p^2-2mid (3p^2-3)-3(p^2-2) =3 $$
So $p^2-2mid 3 implies p^2-2in {-1,1,3}$ which is impossible again.
So the answer is negative if $p$ is prime.
$endgroup$
Partial solution if $p$ is prime.
Write $$3p^4-3p^2+1=n^2implies 3p^2(p^2-1) = (n-1)(n+1)$$
If $pne 2$ (which is not a solution) then $p^2mid n-1$ or $p^2mid n+1 $
First case: If $p^2mid n-1$ then $n+1mid 3p^2-3$ so $ n-1= p^2k$ and $n+1leq 3p^2-3$.
If $kgeq 3$ then $$3p^2-3geq n+1 >n-1 geq 3p^2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2+1$ so $$2p^2+2mid 3p^2-3 implies 2p^2+2mid 2(3p^2-3)-3(2p^2+2) = -12$$
So $p^2+1mid 6 implies p^2+1in {1,2,3,6}$ which is impssible.
$bullet$ If $k=1$ then $n= p^2+1$ so $$p^2+2mid 3p^2-3 implies p^2+2mid (3p^2-3)-3(p^2+2) =-9 $$
So $p^2+2mid 9 implies p^2+2in {1,3,9}$ which is impossible again.
Second case: If $p^2mid n+1$ then $n-1mid 3p^2-3$ so $ n+1= p^2k$ and $n-1leq 3p^2-3$.
Again, if $kgeq 3$ then $$3p^2-3geq n-1 = n+1-2geq 3p^2-2$$ which is impossible. So $kleq 2$
$bullet$ If $k=2$ then $n= 2p^2-1$ so $2p^2-2mid 3p^2-3$ which is impossible.
$bullet$ If $k=1$ then $n= p^2-1$ so $$p^2-2mid 3p^2-3 implies p^2-2mid (3p^2-3)-3(p^2-2) =3 $$
So $p^2-2mid 3 implies p^2-2in {-1,1,3}$ which is impossible again.
So the answer is negative if $p$ is prime.
edited Dec 20 '18 at 11:37
answered Dec 20 '18 at 11:30
Maria MazurMaria Mazur
48.2k1260122
48.2k1260122
1
$begingroup$
what if p is a natural number? Isn't there any way to prove it?
$endgroup$
– eandpiandi
Dec 20 '18 at 12:04
add a comment |
1
$begingroup$
what if p is a natural number? Isn't there any way to prove it?
$endgroup$
– eandpiandi
Dec 20 '18 at 12:04
1
1
$begingroup$
what if p is a natural number? Isn't there any way to prove it?
$endgroup$
– eandpiandi
Dec 20 '18 at 12:04
$begingroup$
what if p is a natural number? Isn't there any way to prove it?
$endgroup$
– eandpiandi
Dec 20 '18 at 12:04
add a comment |
$begingroup$
Hint about method:
$3m^2 - 3m + 1 = n^2$ for any n $in$ Natural, for $p^2 = m$.
$$3m^2 - 3m + 1 - n^2 = 0$$
$$implies m = frac {3 +sqrt{12n^2-3}}6$$
$$implies p^2 = frac {3 +sqrt{12n^2-3}}6$$ or
$$implies p^2 = frac {3 -sqrt{12n^2-3}}6$$
Now you can just make logical comments yourself about this is valid for above given constraints or not, and make out a bit about the equation.
$endgroup$
add a comment |
$begingroup$
Hint about method:
$3m^2 - 3m + 1 = n^2$ for any n $in$ Natural, for $p^2 = m$.
$$3m^2 - 3m + 1 - n^2 = 0$$
$$implies m = frac {3 +sqrt{12n^2-3}}6$$
$$implies p^2 = frac {3 +sqrt{12n^2-3}}6$$ or
$$implies p^2 = frac {3 -sqrt{12n^2-3}}6$$
Now you can just make logical comments yourself about this is valid for above given constraints or not, and make out a bit about the equation.
$endgroup$
add a comment |
$begingroup$
Hint about method:
$3m^2 - 3m + 1 = n^2$ for any n $in$ Natural, for $p^2 = m$.
$$3m^2 - 3m + 1 - n^2 = 0$$
$$implies m = frac {3 +sqrt{12n^2-3}}6$$
$$implies p^2 = frac {3 +sqrt{12n^2-3}}6$$ or
$$implies p^2 = frac {3 -sqrt{12n^2-3}}6$$
Now you can just make logical comments yourself about this is valid for above given constraints or not, and make out a bit about the equation.
$endgroup$
Hint about method:
$3m^2 - 3m + 1 = n^2$ for any n $in$ Natural, for $p^2 = m$.
$$3m^2 - 3m + 1 - n^2 = 0$$
$$implies m = frac {3 +sqrt{12n^2-3}}6$$
$$implies p^2 = frac {3 +sqrt{12n^2-3}}6$$ or
$$implies p^2 = frac {3 -sqrt{12n^2-3}}6$$
Now you can just make logical comments yourself about this is valid for above given constraints or not, and make out a bit about the equation.
edited Dec 20 '18 at 12:17
answered Dec 20 '18 at 11:19
PradyumanDixitPradyumanDixit
847214
847214
add a comment |
add a comment |
$begingroup$
You can compare it with general formula for Pythagorean triples: $(p^2-k^2)^2+(2pk)^2=(p^2+k^2)^2$, we have: $(p^2-1)^2+p^2(2p^2-1)$, here $k=1$ and second term must be $(2p)^2$, which is not, so second term is not competent with that of general formula and your tri-nomial can not be square.
$endgroup$
add a comment |
$begingroup$
You can compare it with general formula for Pythagorean triples: $(p^2-k^2)^2+(2pk)^2=(p^2+k^2)^2$, we have: $(p^2-1)^2+p^2(2p^2-1)$, here $k=1$ and second term must be $(2p)^2$, which is not, so second term is not competent with that of general formula and your tri-nomial can not be square.
$endgroup$
add a comment |
$begingroup$
You can compare it with general formula for Pythagorean triples: $(p^2-k^2)^2+(2pk)^2=(p^2+k^2)^2$, we have: $(p^2-1)^2+p^2(2p^2-1)$, here $k=1$ and second term must be $(2p)^2$, which is not, so second term is not competent with that of general formula and your tri-nomial can not be square.
$endgroup$
You can compare it with general formula for Pythagorean triples: $(p^2-k^2)^2+(2pk)^2=(p^2+k^2)^2$, we have: $(p^2-1)^2+p^2(2p^2-1)$, here $k=1$ and second term must be $(2p)^2$, which is not, so second term is not competent with that of general formula and your tri-nomial can not be square.
answered Dec 20 '18 at 15:32
siroussirous
1,6851514
1,6851514
add a comment |
add a comment |
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$p = 1$ is a square number.
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– Toby Mak
Dec 20 '18 at 11:14
5
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PEOPLE, please stop using $p$ for natural number! Usualy it is $n$ for natural and $p$ for prime. I did whole analisys for nothing.
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– Maria Mazur
Dec 20 '18 at 11:33
1
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You must be fun at parties.
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– Lucas Henrique
Dec 20 '18 at 11:47
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@LucasHenrique Who are you reffering to and what does that have with a math?
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– Maria Mazur
Dec 20 '18 at 12:37