Prove if n is an odd integer, then 3n is odd.If the square of an integer is odd, then the integer is oddIf $n^2+10$ is odd then $n$ is odd.Proof that an odd integer multiplied by $3$ and squared is always oddLet c be an integer which is not divisible by 3. Then the equation $x^3 − x = c$ has no integer solutions.Proving that if $n in mathbbZ$ and $n^2 − 6n + 5$ is even, then $n$ must be odd.Prove: if $x$ is even, then $x + 5$ is odd.Prove that $n^4-n^2$ is divisible by $8$ if $n$ is an odd positive integer.Proof: Given that $x$ is a positive integer, prove…Prove that,if $n$ is an integer, then $n^2 + 15n = 1$ is oddProve that $n! > n^3$ for every integer $n ge 6$ using induction
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Prove if n is an odd integer, then 3n is odd.
If the square of an integer is odd, then the integer is oddIf $n^2+10$ is odd then $n$ is odd.Proof that an odd integer multiplied by $3$ and squared is always oddLet c be an integer which is not divisible by 3. Then the equation $x^3 − x = c$ has no integer solutions.Proving that if $n in mathbbZ$ and $n^2 − 6n + 5$ is even, then $n$ must be odd.Prove: if $x$ is even, then $x + 5$ is odd.Prove that $n^4-n^2$ is divisible by $8$ if $n$ is an odd positive integer.Proof: Given that $x$ is a positive integer, prove…Prove that,if $n$ is an integer, then $n^2 + 15n = 1$ is oddProve that $n! > n^3$ for every integer $n ge 6$ using induction
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
So far I have:
Assume $n$ is odd, $n = 2k+1$ for some integer $k$.
Thenbeginalign3n&= 3(2k+1)\
&= 6k + 3endalign
I'm unsure where to go from here.
elementary-number-theory
$endgroup$
add a comment |
$begingroup$
So far I have:
Assume $n$ is odd, $n = 2k+1$ for some integer $k$.
Thenbeginalign3n&= 3(2k+1)\
&= 6k + 3endalign
I'm unsure where to go from here.
elementary-number-theory
$endgroup$
$begingroup$
Can you find an integer $z$ such that your $3k$ is $3z+1$?
$endgroup$
– Ethan Bolker
9 hours ago
$begingroup$
$6k$ is even. Add $3$ to it gives....
$endgroup$
– David G. Stork
9 hours ago
add a comment |
$begingroup$
So far I have:
Assume $n$ is odd, $n = 2k+1$ for some integer $k$.
Thenbeginalign3n&= 3(2k+1)\
&= 6k + 3endalign
I'm unsure where to go from here.
elementary-number-theory
$endgroup$
So far I have:
Assume $n$ is odd, $n = 2k+1$ for some integer $k$.
Thenbeginalign3n&= 3(2k+1)\
&= 6k + 3endalign
I'm unsure where to go from here.
elementary-number-theory
elementary-number-theory
edited 9 hours ago
José Carlos Santos
204k25 gold badges159 silver badges280 bronze badges
204k25 gold badges159 silver badges280 bronze badges
asked 9 hours ago
Amanda_CAmanda_C
236 bronze badges
236 bronze badges
$begingroup$
Can you find an integer $z$ such that your $3k$ is $3z+1$?
$endgroup$
– Ethan Bolker
9 hours ago
$begingroup$
$6k$ is even. Add $3$ to it gives....
$endgroup$
– David G. Stork
9 hours ago
add a comment |
$begingroup$
Can you find an integer $z$ such that your $3k$ is $3z+1$?
$endgroup$
– Ethan Bolker
9 hours ago
$begingroup$
$6k$ is even. Add $3$ to it gives....
$endgroup$
– David G. Stork
9 hours ago
$begingroup$
Can you find an integer $z$ such that your $3k$ is $3z+1$?
$endgroup$
– Ethan Bolker
9 hours ago
$begingroup$
Can you find an integer $z$ such that your $3k$ is $3z+1$?
$endgroup$
– Ethan Bolker
9 hours ago
$begingroup$
$6k$ is even. Add $3$ to it gives....
$endgroup$
– David G. Stork
9 hours ago
$begingroup$
$6k$ is even. Add $3$ to it gives....
$endgroup$
– David G. Stork
9 hours ago
add a comment |
6 Answers
6
active
oldest
votes
$begingroup$
Use the fact that $6k+3=2(3k+1)+1$.
$endgroup$
$begingroup$
How does the 2(3𝑘+1)+1 help?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
Because the odd integers are precisely those that can be written as $2N+1$.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
and so that means I can then write 2N + 1 where the N is actually the 3k + 1 ,,,which means its odd and the proof is true?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
A proof is neither true nor false. But if you add that $6k+3=2(2k+1)+1$, then it will be a correct proof.
$endgroup$
– José Carlos Santos
9 hours ago
add a comment |
$begingroup$
Since $2n$ is even, we have $3n=2n+n$ as a sum of an odd number and an even number, which is obviously odd.
$endgroup$
add a comment |
$begingroup$
Take $$n=2k+1$$ this is an odd number, then $$3(2k+1)=6k+3=(6k+2)+1$$ this is also an odd number.
$endgroup$
add a comment |
$begingroup$
Let $n$ be an odd integer.
Then $3n$ is the product of two odd integers, and thus odd.
$endgroup$
add a comment |
$begingroup$
Let $n in mathbbZ$ be odd, so $n = 2m + 1$ for some $m in mathbbZ$. We have:
beginalign*
3n = 3(2m+1) = 6m + 3 = 2(3m + 1) + 1,
endalign*
where $3m + 1 in mathbbZ$ by closure. Let $z = 3m + 1$, so we have
beginalign*
3n = 2z + 1.
endalign*
Thus, $3n$ is odd.
$endgroup$
add a comment |
$begingroup$
$6k + 3$ can be written as $6k + 2 + 1$, now factoring we get $2(3k+1) + 1$, let $(3k+1) = A$, then $2A + 1$ is odd. in general, multiplying an odd integer with an odd integer always yields an odd integer. It is a good idea to prove it, you can also prove it with induction.
$endgroup$
add a comment |
Your Answer
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6 Answers
6
active
oldest
votes
6 Answers
6
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Use the fact that $6k+3=2(3k+1)+1$.
$endgroup$
$begingroup$
How does the 2(3𝑘+1)+1 help?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
Because the odd integers are precisely those that can be written as $2N+1$.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
and so that means I can then write 2N + 1 where the N is actually the 3k + 1 ,,,which means its odd and the proof is true?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
A proof is neither true nor false. But if you add that $6k+3=2(2k+1)+1$, then it will be a correct proof.
$endgroup$
– José Carlos Santos
9 hours ago
add a comment |
$begingroup$
Use the fact that $6k+3=2(3k+1)+1$.
$endgroup$
$begingroup$
How does the 2(3𝑘+1)+1 help?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
Because the odd integers are precisely those that can be written as $2N+1$.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
and so that means I can then write 2N + 1 where the N is actually the 3k + 1 ,,,which means its odd and the proof is true?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
A proof is neither true nor false. But if you add that $6k+3=2(2k+1)+1$, then it will be a correct proof.
$endgroup$
– José Carlos Santos
9 hours ago
add a comment |
$begingroup$
Use the fact that $6k+3=2(3k+1)+1$.
$endgroup$
Use the fact that $6k+3=2(3k+1)+1$.
answered 9 hours ago
José Carlos SantosJosé Carlos Santos
204k25 gold badges159 silver badges280 bronze badges
204k25 gold badges159 silver badges280 bronze badges
$begingroup$
How does the 2(3𝑘+1)+1 help?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
Because the odd integers are precisely those that can be written as $2N+1$.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
and so that means I can then write 2N + 1 where the N is actually the 3k + 1 ,,,which means its odd and the proof is true?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
A proof is neither true nor false. But if you add that $6k+3=2(2k+1)+1$, then it will be a correct proof.
$endgroup$
– José Carlos Santos
9 hours ago
add a comment |
$begingroup$
How does the 2(3𝑘+1)+1 help?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
Because the odd integers are precisely those that can be written as $2N+1$.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
and so that means I can then write 2N + 1 where the N is actually the 3k + 1 ,,,which means its odd and the proof is true?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
A proof is neither true nor false. But if you add that $6k+3=2(2k+1)+1$, then it will be a correct proof.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
How does the 2(3𝑘+1)+1 help?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
How does the 2(3𝑘+1)+1 help?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
Because the odd integers are precisely those that can be written as $2N+1$.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
Because the odd integers are precisely those that can be written as $2N+1$.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
and so that means I can then write 2N + 1 where the N is actually the 3k + 1 ,,,which means its odd and the proof is true?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
and so that means I can then write 2N + 1 where the N is actually the 3k + 1 ,,,which means its odd and the proof is true?
$endgroup$
– Amanda_C
9 hours ago
$begingroup$
A proof is neither true nor false. But if you add that $6k+3=2(2k+1)+1$, then it will be a correct proof.
$endgroup$
– José Carlos Santos
9 hours ago
$begingroup$
A proof is neither true nor false. But if you add that $6k+3=2(2k+1)+1$, then it will be a correct proof.
$endgroup$
– José Carlos Santos
9 hours ago
add a comment |
$begingroup$
Since $2n$ is even, we have $3n=2n+n$ as a sum of an odd number and an even number, which is obviously odd.
$endgroup$
add a comment |
$begingroup$
Since $2n$ is even, we have $3n=2n+n$ as a sum of an odd number and an even number, which is obviously odd.
$endgroup$
add a comment |
$begingroup$
Since $2n$ is even, we have $3n=2n+n$ as a sum of an odd number and an even number, which is obviously odd.
$endgroup$
Since $2n$ is even, we have $3n=2n+n$ as a sum of an odd number and an even number, which is obviously odd.
answered 9 hours ago
szw1710szw1710
6,83712 silver badges23 bronze badges
6,83712 silver badges23 bronze badges
add a comment |
add a comment |
$begingroup$
Take $$n=2k+1$$ this is an odd number, then $$3(2k+1)=6k+3=(6k+2)+1$$ this is also an odd number.
$endgroup$
add a comment |
$begingroup$
Take $$n=2k+1$$ this is an odd number, then $$3(2k+1)=6k+3=(6k+2)+1$$ this is also an odd number.
$endgroup$
add a comment |
$begingroup$
Take $$n=2k+1$$ this is an odd number, then $$3(2k+1)=6k+3=(6k+2)+1$$ this is also an odd number.
$endgroup$
Take $$n=2k+1$$ this is an odd number, then $$3(2k+1)=6k+3=(6k+2)+1$$ this is also an odd number.
answered 9 hours ago
Dr. Sonnhard GraubnerDr. Sonnhard Graubner
86k4 gold badges29 silver badges69 bronze badges
86k4 gold badges29 silver badges69 bronze badges
add a comment |
add a comment |
$begingroup$
Let $n$ be an odd integer.
Then $3n$ is the product of two odd integers, and thus odd.
$endgroup$
add a comment |
$begingroup$
Let $n$ be an odd integer.
Then $3n$ is the product of two odd integers, and thus odd.
$endgroup$
add a comment |
$begingroup$
Let $n$ be an odd integer.
Then $3n$ is the product of two odd integers, and thus odd.
$endgroup$
Let $n$ be an odd integer.
Then $3n$ is the product of two odd integers, and thus odd.
edited 3 hours ago
answered 7 hours ago
mlchristiansmlchristians
2,0852 silver badges19 bronze badges
2,0852 silver badges19 bronze badges
add a comment |
add a comment |
$begingroup$
Let $n in mathbbZ$ be odd, so $n = 2m + 1$ for some $m in mathbbZ$. We have:
beginalign*
3n = 3(2m+1) = 6m + 3 = 2(3m + 1) + 1,
endalign*
where $3m + 1 in mathbbZ$ by closure. Let $z = 3m + 1$, so we have
beginalign*
3n = 2z + 1.
endalign*
Thus, $3n$ is odd.
$endgroup$
add a comment |
$begingroup$
Let $n in mathbbZ$ be odd, so $n = 2m + 1$ for some $m in mathbbZ$. We have:
beginalign*
3n = 3(2m+1) = 6m + 3 = 2(3m + 1) + 1,
endalign*
where $3m + 1 in mathbbZ$ by closure. Let $z = 3m + 1$, so we have
beginalign*
3n = 2z + 1.
endalign*
Thus, $3n$ is odd.
$endgroup$
add a comment |
$begingroup$
Let $n in mathbbZ$ be odd, so $n = 2m + 1$ for some $m in mathbbZ$. We have:
beginalign*
3n = 3(2m+1) = 6m + 3 = 2(3m + 1) + 1,
endalign*
where $3m + 1 in mathbbZ$ by closure. Let $z = 3m + 1$, so we have
beginalign*
3n = 2z + 1.
endalign*
Thus, $3n$ is odd.
$endgroup$
Let $n in mathbbZ$ be odd, so $n = 2m + 1$ for some $m in mathbbZ$. We have:
beginalign*
3n = 3(2m+1) = 6m + 3 = 2(3m + 1) + 1,
endalign*
where $3m + 1 in mathbbZ$ by closure. Let $z = 3m + 1$, so we have
beginalign*
3n = 2z + 1.
endalign*
Thus, $3n$ is odd.
answered 8 hours ago
Matt.PMatt.P
1,2015 silver badges19 bronze badges
1,2015 silver badges19 bronze badges
add a comment |
add a comment |
$begingroup$
$6k + 3$ can be written as $6k + 2 + 1$, now factoring we get $2(3k+1) + 1$, let $(3k+1) = A$, then $2A + 1$ is odd. in general, multiplying an odd integer with an odd integer always yields an odd integer. It is a good idea to prove it, you can also prove it with induction.
$endgroup$
add a comment |
$begingroup$
$6k + 3$ can be written as $6k + 2 + 1$, now factoring we get $2(3k+1) + 1$, let $(3k+1) = A$, then $2A + 1$ is odd. in general, multiplying an odd integer with an odd integer always yields an odd integer. It is a good idea to prove it, you can also prove it with induction.
$endgroup$
add a comment |
$begingroup$
$6k + 3$ can be written as $6k + 2 + 1$, now factoring we get $2(3k+1) + 1$, let $(3k+1) = A$, then $2A + 1$ is odd. in general, multiplying an odd integer with an odd integer always yields an odd integer. It is a good idea to prove it, you can also prove it with induction.
$endgroup$
$6k + 3$ can be written as $6k + 2 + 1$, now factoring we get $2(3k+1) + 1$, let $(3k+1) = A$, then $2A + 1$ is odd. in general, multiplying an odd integer with an odd integer always yields an odd integer. It is a good idea to prove it, you can also prove it with induction.
answered 8 hours ago
Donlans DonlansDonlans Donlans
275 bronze badges
275 bronze badges
add a comment |
add a comment |
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$begingroup$
Can you find an integer $z$ such that your $3k$ is $3z+1$?
$endgroup$
– Ethan Bolker
9 hours ago
$begingroup$
$6k$ is even. Add $3$ to it gives....
$endgroup$
– David G. Stork
9 hours ago