How to Show that $[2]_6$ and $[3]_9$ are disjoint
I’m not sure how to prove this. Specifically, I don’t fully understand congruence class modulo m to prove these sets are disjoint.
elementary-set-theory proof-writing proof-explanation
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I’m not sure how to prove this. Specifically, I don’t fully understand congruence class modulo m to prove these sets are disjoint.
elementary-set-theory proof-writing proof-explanation
add a comment |
I’m not sure how to prove this. Specifically, I don’t fully understand congruence class modulo m to prove these sets are disjoint.
elementary-set-theory proof-writing proof-explanation
I’m not sure how to prove this. Specifically, I don’t fully understand congruence class modulo m to prove these sets are disjoint.
elementary-set-theory proof-writing proof-explanation
elementary-set-theory proof-writing proof-explanation
edited Dec 2 at 1:55
asked Dec 2 at 1:43
darylnak
158111
158111
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4 Answers
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Hint $ 3 + 9x = 2+6y iff color{#c00}1 = 6y-9x = color{#c00}3(2y-3x)$
Or $ nequiv 2pmod{!6},Rightarrow, nequiv color{#0a0}2pmod{!3} $ by $ 2+6j = 2+3(2j)$
but $, nequiv 3pmod{!9},Rightarrow, nequiv color{#0a0}3pmod{!3}$
add a comment |
$[2]_6$ is the set of all integers which have $2$ as remainder when divided by $6$, and $[3]_9$ is the set of all integers which have $3$ as remainder when divided by $9$. So an integer $x$ in both congruence classes could be written as
$$x=2+6k=3+9ell$$
which implies $$3-2=1=6k-9ell.$$
Can you why there is a problem?
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:55
add a comment |
You can think of the congruence class modulo $m$ to be the set of numbers with remainder $n$ when divided by $m$ (where $n<m$).
Once you have that, no integer can have two different remainders, then it must be in at most one of these sets, maybe neither.
add a comment |
If I understand your notation, $[2]_6$ consists of all the numbers congruent to $2$ modulo $6$. Those are the numbers that leave a remainder of $2$ when you divide by $6$, so
$$
[2]_6 = { ldots , -10, -4, 2, 8, 14, ldots}.
$$
Can you finish now? Write down $[3]_6$ and check whether it and ${2}_6$ have any numbers in common.
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:56
Well write that one down and see if it overlaps $[2]_6$.
– Ethan Bolker
Dec 2 at 2:19
add a comment |
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
Hint $ 3 + 9x = 2+6y iff color{#c00}1 = 6y-9x = color{#c00}3(2y-3x)$
Or $ nequiv 2pmod{!6},Rightarrow, nequiv color{#0a0}2pmod{!3} $ by $ 2+6j = 2+3(2j)$
but $, nequiv 3pmod{!9},Rightarrow, nequiv color{#0a0}3pmod{!3}$
add a comment |
Hint $ 3 + 9x = 2+6y iff color{#c00}1 = 6y-9x = color{#c00}3(2y-3x)$
Or $ nequiv 2pmod{!6},Rightarrow, nequiv color{#0a0}2pmod{!3} $ by $ 2+6j = 2+3(2j)$
but $, nequiv 3pmod{!9},Rightarrow, nequiv color{#0a0}3pmod{!3}$
add a comment |
Hint $ 3 + 9x = 2+6y iff color{#c00}1 = 6y-9x = color{#c00}3(2y-3x)$
Or $ nequiv 2pmod{!6},Rightarrow, nequiv color{#0a0}2pmod{!3} $ by $ 2+6j = 2+3(2j)$
but $, nequiv 3pmod{!9},Rightarrow, nequiv color{#0a0}3pmod{!3}$
Hint $ 3 + 9x = 2+6y iff color{#c00}1 = 6y-9x = color{#c00}3(2y-3x)$
Or $ nequiv 2pmod{!6},Rightarrow, nequiv color{#0a0}2pmod{!3} $ by $ 2+6j = 2+3(2j)$
but $, nequiv 3pmod{!9},Rightarrow, nequiv color{#0a0}3pmod{!3}$
edited Dec 2 at 2:14
answered Dec 2 at 2:05
Bill Dubuque
208k29190628
208k29190628
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$[2]_6$ is the set of all integers which have $2$ as remainder when divided by $6$, and $[3]_9$ is the set of all integers which have $3$ as remainder when divided by $9$. So an integer $x$ in both congruence classes could be written as
$$x=2+6k=3+9ell$$
which implies $$3-2=1=6k-9ell.$$
Can you why there is a problem?
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:55
add a comment |
$[2]_6$ is the set of all integers which have $2$ as remainder when divided by $6$, and $[3]_9$ is the set of all integers which have $3$ as remainder when divided by $9$. So an integer $x$ in both congruence classes could be written as
$$x=2+6k=3+9ell$$
which implies $$3-2=1=6k-9ell.$$
Can you why there is a problem?
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:55
add a comment |
$[2]_6$ is the set of all integers which have $2$ as remainder when divided by $6$, and $[3]_9$ is the set of all integers which have $3$ as remainder when divided by $9$. So an integer $x$ in both congruence classes could be written as
$$x=2+6k=3+9ell$$
which implies $$3-2=1=6k-9ell.$$
Can you why there is a problem?
$[2]_6$ is the set of all integers which have $2$ as remainder when divided by $6$, and $[3]_9$ is the set of all integers which have $3$ as remainder when divided by $9$. So an integer $x$ in both congruence classes could be written as
$$x=2+6k=3+9ell$$
which implies $$3-2=1=6k-9ell.$$
Can you why there is a problem?
edited Dec 2 at 2:04
answered Dec 2 at 1:51
Bernard
118k639112
118k639112
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:55
add a comment |
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:55
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:55
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:55
add a comment |
You can think of the congruence class modulo $m$ to be the set of numbers with remainder $n$ when divided by $m$ (where $n<m$).
Once you have that, no integer can have two different remainders, then it must be in at most one of these sets, maybe neither.
add a comment |
You can think of the congruence class modulo $m$ to be the set of numbers with remainder $n$ when divided by $m$ (where $n<m$).
Once you have that, no integer can have two different remainders, then it must be in at most one of these sets, maybe neither.
add a comment |
You can think of the congruence class modulo $m$ to be the set of numbers with remainder $n$ when divided by $m$ (where $n<m$).
Once you have that, no integer can have two different remainders, then it must be in at most one of these sets, maybe neither.
You can think of the congruence class modulo $m$ to be the set of numbers with remainder $n$ when divided by $m$ (where $n<m$).
Once you have that, no integer can have two different remainders, then it must be in at most one of these sets, maybe neither.
answered Dec 2 at 1:49
NL1992
8311
8311
add a comment |
add a comment |
If I understand your notation, $[2]_6$ consists of all the numbers congruent to $2$ modulo $6$. Those are the numbers that leave a remainder of $2$ when you divide by $6$, so
$$
[2]_6 = { ldots , -10, -4, 2, 8, 14, ldots}.
$$
Can you finish now? Write down $[3]_6$ and check whether it and ${2}_6$ have any numbers in common.
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:56
Well write that one down and see if it overlaps $[2]_6$.
– Ethan Bolker
Dec 2 at 2:19
add a comment |
If I understand your notation, $[2]_6$ consists of all the numbers congruent to $2$ modulo $6$. Those are the numbers that leave a remainder of $2$ when you divide by $6$, so
$$
[2]_6 = { ldots , -10, -4, 2, 8, 14, ldots}.
$$
Can you finish now? Write down $[3]_6$ and check whether it and ${2}_6$ have any numbers in common.
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:56
Well write that one down and see if it overlaps $[2]_6$.
– Ethan Bolker
Dec 2 at 2:19
add a comment |
If I understand your notation, $[2]_6$ consists of all the numbers congruent to $2$ modulo $6$. Those are the numbers that leave a remainder of $2$ when you divide by $6$, so
$$
[2]_6 = { ldots , -10, -4, 2, 8, 14, ldots}.
$$
Can you finish now? Write down $[3]_6$ and check whether it and ${2}_6$ have any numbers in common.
If I understand your notation, $[2]_6$ consists of all the numbers congruent to $2$ modulo $6$. Those are the numbers that leave a remainder of $2$ when you divide by $6$, so
$$
[2]_6 = { ldots , -10, -4, 2, 8, 14, ldots}.
$$
Can you finish now? Write down $[3]_6$ and check whether it and ${2}_6$ have any numbers in common.
answered Dec 2 at 1:48
Ethan Bolker
41.2k547108
41.2k547108
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:56
Well write that one down and see if it overlaps $[2]_6$.
– Ethan Bolker
Dec 2 at 2:19
add a comment |
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:56
Well write that one down and see if it overlaps $[2]_6$.
– Ethan Bolker
Dec 2 at 2:19
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:56
There was an error in my question. It should have been [3]_9
– darylnak
Dec 2 at 1:56
Well write that one down and see if it overlaps $[2]_6$.
– Ethan Bolker
Dec 2 at 2:19
Well write that one down and see if it overlaps $[2]_6$.
– Ethan Bolker
Dec 2 at 2:19
add a comment |
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