Solving $472x ≡ 32 ;(text{mod } 92)$: How to solve when $a$ is greater than $m$
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I'm not sure where to begin here. I think that I can change the $472x$ to be $12x$ because they should be equal in mod $92$. Then, I believe I can simplify the equation to be: $3x ≡ 8 ; (text{mod } 23)$
modular-arithmetic
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add a comment |
$begingroup$
I'm not sure where to begin here. I think that I can change the $472x$ to be $12x$ because they should be equal in mod $92$. Then, I believe I can simplify the equation to be: $3x ≡ 8 ; (text{mod } 23)$
modular-arithmetic
$endgroup$
$begingroup$
You're almost done: $bmod 23!:, 3xequiv 8equiv -15,$ so $,xequiv -5 $
$endgroup$
– Bill Dubuque
Dec 26 '18 at 0:47
add a comment |
$begingroup$
I'm not sure where to begin here. I think that I can change the $472x$ to be $12x$ because they should be equal in mod $92$. Then, I believe I can simplify the equation to be: $3x ≡ 8 ; (text{mod } 23)$
modular-arithmetic
$endgroup$
I'm not sure where to begin here. I think that I can change the $472x$ to be $12x$ because they should be equal in mod $92$. Then, I believe I can simplify the equation to be: $3x ≡ 8 ; (text{mod } 23)$
modular-arithmetic
modular-arithmetic
edited Dec 10 '18 at 20:56
MisterRiemann
5,8121625
5,8121625
asked Dec 10 '18 at 20:39
user52640user52640
453
453
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You're almost done: $bmod 23!:, 3xequiv 8equiv -15,$ so $,xequiv -5 $
$endgroup$
– Bill Dubuque
Dec 26 '18 at 0:47
add a comment |
$begingroup$
You're almost done: $bmod 23!:, 3xequiv 8equiv -15,$ so $,xequiv -5 $
$endgroup$
– Bill Dubuque
Dec 26 '18 at 0:47
$begingroup$
You're almost done: $bmod 23!:, 3xequiv 8equiv -15,$ so $,xequiv -5 $
$endgroup$
– Bill Dubuque
Dec 26 '18 at 0:47
$begingroup$
You're almost done: $bmod 23!:, 3xequiv 8equiv -15,$ so $,xequiv -5 $
$endgroup$
– Bill Dubuque
Dec 26 '18 at 0:47
add a comment |
1 Answer
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$begingroup$
You're on the right track. Starting from
$$ 3x equiv 8 ; (text{mod } 23), $$
you should find the multiplicative inverse $3^{-1}$ of $3$ modulo $23$, i.e. the number satisfying
$$ 3^{-1} cdot 3 equiv 1 ; (text{mod } 23). $$
This can be done with the help of the Euclidean algorithm, or alternatively you could just notice that
$$ 8cdot 3 = 24 equiv 1 ; (text{mod } 23), $$
so $3^{-1} = 8$ in this case. Then you can multiply both sides of your equation by this multiplicative inverse to obtain
$$ x equiv 8cdot 3 x equiv 8 cdot 8 = 64 equiv 18 ; (text{mod } 23). $$
Hence $x = 18+23k$, for an integer $k$, so you get four incongruent solutions (modulo $92$) to your original equation, namely by inserting $k=0,1,2,3$.
$endgroup$
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1 Answer
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$begingroup$
You're on the right track. Starting from
$$ 3x equiv 8 ; (text{mod } 23), $$
you should find the multiplicative inverse $3^{-1}$ of $3$ modulo $23$, i.e. the number satisfying
$$ 3^{-1} cdot 3 equiv 1 ; (text{mod } 23). $$
This can be done with the help of the Euclidean algorithm, or alternatively you could just notice that
$$ 8cdot 3 = 24 equiv 1 ; (text{mod } 23), $$
so $3^{-1} = 8$ in this case. Then you can multiply both sides of your equation by this multiplicative inverse to obtain
$$ x equiv 8cdot 3 x equiv 8 cdot 8 = 64 equiv 18 ; (text{mod } 23). $$
Hence $x = 18+23k$, for an integer $k$, so you get four incongruent solutions (modulo $92$) to your original equation, namely by inserting $k=0,1,2,3$.
$endgroup$
add a comment |
$begingroup$
You're on the right track. Starting from
$$ 3x equiv 8 ; (text{mod } 23), $$
you should find the multiplicative inverse $3^{-1}$ of $3$ modulo $23$, i.e. the number satisfying
$$ 3^{-1} cdot 3 equiv 1 ; (text{mod } 23). $$
This can be done with the help of the Euclidean algorithm, or alternatively you could just notice that
$$ 8cdot 3 = 24 equiv 1 ; (text{mod } 23), $$
so $3^{-1} = 8$ in this case. Then you can multiply both sides of your equation by this multiplicative inverse to obtain
$$ x equiv 8cdot 3 x equiv 8 cdot 8 = 64 equiv 18 ; (text{mod } 23). $$
Hence $x = 18+23k$, for an integer $k$, so you get four incongruent solutions (modulo $92$) to your original equation, namely by inserting $k=0,1,2,3$.
$endgroup$
add a comment |
$begingroup$
You're on the right track. Starting from
$$ 3x equiv 8 ; (text{mod } 23), $$
you should find the multiplicative inverse $3^{-1}$ of $3$ modulo $23$, i.e. the number satisfying
$$ 3^{-1} cdot 3 equiv 1 ; (text{mod } 23). $$
This can be done with the help of the Euclidean algorithm, or alternatively you could just notice that
$$ 8cdot 3 = 24 equiv 1 ; (text{mod } 23), $$
so $3^{-1} = 8$ in this case. Then you can multiply both sides of your equation by this multiplicative inverse to obtain
$$ x equiv 8cdot 3 x equiv 8 cdot 8 = 64 equiv 18 ; (text{mod } 23). $$
Hence $x = 18+23k$, for an integer $k$, so you get four incongruent solutions (modulo $92$) to your original equation, namely by inserting $k=0,1,2,3$.
$endgroup$
You're on the right track. Starting from
$$ 3x equiv 8 ; (text{mod } 23), $$
you should find the multiplicative inverse $3^{-1}$ of $3$ modulo $23$, i.e. the number satisfying
$$ 3^{-1} cdot 3 equiv 1 ; (text{mod } 23). $$
This can be done with the help of the Euclidean algorithm, or alternatively you could just notice that
$$ 8cdot 3 = 24 equiv 1 ; (text{mod } 23), $$
so $3^{-1} = 8$ in this case. Then you can multiply both sides of your equation by this multiplicative inverse to obtain
$$ x equiv 8cdot 3 x equiv 8 cdot 8 = 64 equiv 18 ; (text{mod } 23). $$
Hence $x = 18+23k$, for an integer $k$, so you get four incongruent solutions (modulo $92$) to your original equation, namely by inserting $k=0,1,2,3$.
answered Dec 10 '18 at 20:46
MisterRiemannMisterRiemann
5,8121625
5,8121625
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$begingroup$
You're almost done: $bmod 23!:, 3xequiv 8equiv -15,$ so $,xequiv -5 $
$endgroup$
– Bill Dubuque
Dec 26 '18 at 0:47