Does there exist $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$?
Does there exist $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$? Use the work from part a to justify the answer.
So in part a, I had to prove:
For each $[a] in mathbb Z_5 ,$ if $[a] neq [0] $, then $[a]^2 = [1]$ or $[a]^2=[4]$.
I was able to this, and determined that this was true for all of the cases.
Using the information I found from that part of the question though, I have to prove if there exists $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$.
All that I have been able to write down for my answer so far is:
For each integer $a$, if $ a ncong 0 (mod5)$, then $a^2 cong 1 (mod5)$ or $ a^2 cong 4 (mod5)$ and integer $n$ is a perfect square if $exists k in mathbb Z : n=k^2.$
I'm not sure where to go from here, any help would be appreciated!
equivalence-relations
|
show 1 more comment
Does there exist $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$? Use the work from part a to justify the answer.
So in part a, I had to prove:
For each $[a] in mathbb Z_5 ,$ if $[a] neq [0] $, then $[a]^2 = [1]$ or $[a]^2=[4]$.
I was able to this, and determined that this was true for all of the cases.
Using the information I found from that part of the question though, I have to prove if there exists $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$.
All that I have been able to write down for my answer so far is:
For each integer $a$, if $ a ncong 0 (mod5)$, then $a^2 cong 1 (mod5)$ or $ a^2 cong 4 (mod5)$ and integer $n$ is a perfect square if $exists k in mathbb Z : n=k^2.$
I'm not sure where to go from here, any help would be appreciated!
equivalence-relations
Well, if such an $a$ existed then $a^2$ is $3$ modulo $5$. Do you see the problem?
– T. Bongers
Nov 30 '18 at 2:46
where did you get the 3 from ? @T.Bongers
– Claire
Nov 30 '18 at 2:51
@Claire you number $5,158,232,468,953,153$ end with digit $3$.
– achille hui
Nov 30 '18 at 2:53
Is $5,158,232,468,953,153cong 1,4 pmod 5$?
– fleablood
Nov 30 '18 at 2:53
can any square number have 3 as the last digit.
– karakfa
Nov 30 '18 at 2:53
|
show 1 more comment
Does there exist $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$? Use the work from part a to justify the answer.
So in part a, I had to prove:
For each $[a] in mathbb Z_5 ,$ if $[a] neq [0] $, then $[a]^2 = [1]$ or $[a]^2=[4]$.
I was able to this, and determined that this was true for all of the cases.
Using the information I found from that part of the question though, I have to prove if there exists $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$.
All that I have been able to write down for my answer so far is:
For each integer $a$, if $ a ncong 0 (mod5)$, then $a^2 cong 1 (mod5)$ or $ a^2 cong 4 (mod5)$ and integer $n$ is a perfect square if $exists k in mathbb Z : n=k^2.$
I'm not sure where to go from here, any help would be appreciated!
equivalence-relations
Does there exist $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$? Use the work from part a to justify the answer.
So in part a, I had to prove:
For each $[a] in mathbb Z_5 ,$ if $[a] neq [0] $, then $[a]^2 = [1]$ or $[a]^2=[4]$.
I was able to this, and determined that this was true for all of the cases.
Using the information I found from that part of the question though, I have to prove if there exists $a in mathbb Z$ such that $a^2 = 5,158, 232,468,953,153$.
All that I have been able to write down for my answer so far is:
For each integer $a$, if $ a ncong 0 (mod5)$, then $a^2 cong 1 (mod5)$ or $ a^2 cong 4 (mod5)$ and integer $n$ is a perfect square if $exists k in mathbb Z : n=k^2.$
I'm not sure where to go from here, any help would be appreciated!
equivalence-relations
equivalence-relations
edited Nov 30 '18 at 3:37
Robert Howard
1,9161822
1,9161822
asked Nov 30 '18 at 2:40
ClaireClaire
556
556
Well, if such an $a$ existed then $a^2$ is $3$ modulo $5$. Do you see the problem?
– T. Bongers
Nov 30 '18 at 2:46
where did you get the 3 from ? @T.Bongers
– Claire
Nov 30 '18 at 2:51
@Claire you number $5,158,232,468,953,153$ end with digit $3$.
– achille hui
Nov 30 '18 at 2:53
Is $5,158,232,468,953,153cong 1,4 pmod 5$?
– fleablood
Nov 30 '18 at 2:53
can any square number have 3 as the last digit.
– karakfa
Nov 30 '18 at 2:53
|
show 1 more comment
Well, if such an $a$ existed then $a^2$ is $3$ modulo $5$. Do you see the problem?
– T. Bongers
Nov 30 '18 at 2:46
where did you get the 3 from ? @T.Bongers
– Claire
Nov 30 '18 at 2:51
@Claire you number $5,158,232,468,953,153$ end with digit $3$.
– achille hui
Nov 30 '18 at 2:53
Is $5,158,232,468,953,153cong 1,4 pmod 5$?
– fleablood
Nov 30 '18 at 2:53
can any square number have 3 as the last digit.
– karakfa
Nov 30 '18 at 2:53
Well, if such an $a$ existed then $a^2$ is $3$ modulo $5$. Do you see the problem?
– T. Bongers
Nov 30 '18 at 2:46
Well, if such an $a$ existed then $a^2$ is $3$ modulo $5$. Do you see the problem?
– T. Bongers
Nov 30 '18 at 2:46
where did you get the 3 from ? @T.Bongers
– Claire
Nov 30 '18 at 2:51
where did you get the 3 from ? @T.Bongers
– Claire
Nov 30 '18 at 2:51
@Claire you number $5,158,232,468,953,153$ end with digit $3$.
– achille hui
Nov 30 '18 at 2:53
@Claire you number $5,158,232,468,953,153$ end with digit $3$.
– achille hui
Nov 30 '18 at 2:53
Is $5,158,232,468,953,153cong 1,4 pmod 5$?
– fleablood
Nov 30 '18 at 2:53
Is $5,158,232,468,953,153cong 1,4 pmod 5$?
– fleablood
Nov 30 '18 at 2:53
can any square number have 3 as the last digit.
– karakfa
Nov 30 '18 at 2:53
can any square number have 3 as the last digit.
– karakfa
Nov 30 '18 at 2:53
|
show 1 more comment
2 Answers
2
active
oldest
votes
So start by writing down the squares of the integers from $1,ldots,10$. Note that they end in only one of ${1,4,6,9}$. It is also easy to see that the last digit of a perfect square depends only on the last digit of its square root (write the square root as $10k+a$). You'll then see that any perfect square ends in one of the above digits, and 3 is not one of them. It also follows from the fact that you already found out that a perfect square is congruent module $1$ or $4$ to 5, which is essentially the same statement. Clearly, any integer which has $3$ as its last digit is congruent modulo $3$, which is a contradiction. PS: integers which are multiples of $10$ end with a $0$ (in fact, two of them), but I assume you aren't considering squares of $0$ when you look at $mathbb Z_5$.
add a comment |
You yourself wrote down
For each integer a,if a≆0 (mod 5),then a^2≅1(mod 5) or a^2≅4(mod 5)
Does $a^2 = 5,158,232,468,953,153$ satisfy those conditions?
However you have to consider that maybe $a cong 0 pmod 5$. In which case $a^2 cong 0 pmod 5$. Do $a^2$ satisfy that condition either?
No, because either way, the number doesn't end in a 0 or a 5, so it's not divisible by 5. The 0 condition isn't satisified either because perfect squares only end in 1, 4, 6, or 9
– Claire
Nov 30 '18 at 2:59
Is this the reason why it's not true then? @fleablood
– Claire
Nov 30 '18 at 3:18
Well, you DID say $a^2$ must be equiv $1$ or $4$ mod $5$. Or $a$ equiv $0$. And $5,1....,.53$ is not that. So you tell me. Is it possible for something to happen that you yourself proved could not happen?
– fleablood
Nov 30 '18 at 4:27
But perfect squares like 100, 400, 900, 1600, etc. can and with $0$.
– fleablood
Nov 30 '18 at 4:28
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
});
});
}, "mathjax-editing");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "69"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3019548%2fdoes-there-exist-a-in-mathbb-z-such-that-a2-5-158-232-468-953-153%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
So start by writing down the squares of the integers from $1,ldots,10$. Note that they end in only one of ${1,4,6,9}$. It is also easy to see that the last digit of a perfect square depends only on the last digit of its square root (write the square root as $10k+a$). You'll then see that any perfect square ends in one of the above digits, and 3 is not one of them. It also follows from the fact that you already found out that a perfect square is congruent module $1$ or $4$ to 5, which is essentially the same statement. Clearly, any integer which has $3$ as its last digit is congruent modulo $3$, which is a contradiction. PS: integers which are multiples of $10$ end with a $0$ (in fact, two of them), but I assume you aren't considering squares of $0$ when you look at $mathbb Z_5$.
add a comment |
So start by writing down the squares of the integers from $1,ldots,10$. Note that they end in only one of ${1,4,6,9}$. It is also easy to see that the last digit of a perfect square depends only on the last digit of its square root (write the square root as $10k+a$). You'll then see that any perfect square ends in one of the above digits, and 3 is not one of them. It also follows from the fact that you already found out that a perfect square is congruent module $1$ or $4$ to 5, which is essentially the same statement. Clearly, any integer which has $3$ as its last digit is congruent modulo $3$, which is a contradiction. PS: integers which are multiples of $10$ end with a $0$ (in fact, two of them), but I assume you aren't considering squares of $0$ when you look at $mathbb Z_5$.
add a comment |
So start by writing down the squares of the integers from $1,ldots,10$. Note that they end in only one of ${1,4,6,9}$. It is also easy to see that the last digit of a perfect square depends only on the last digit of its square root (write the square root as $10k+a$). You'll then see that any perfect square ends in one of the above digits, and 3 is not one of them. It also follows from the fact that you already found out that a perfect square is congruent module $1$ or $4$ to 5, which is essentially the same statement. Clearly, any integer which has $3$ as its last digit is congruent modulo $3$, which is a contradiction. PS: integers which are multiples of $10$ end with a $0$ (in fact, two of them), but I assume you aren't considering squares of $0$ when you look at $mathbb Z_5$.
So start by writing down the squares of the integers from $1,ldots,10$. Note that they end in only one of ${1,4,6,9}$. It is also easy to see that the last digit of a perfect square depends only on the last digit of its square root (write the square root as $10k+a$). You'll then see that any perfect square ends in one of the above digits, and 3 is not one of them. It also follows from the fact that you already found out that a perfect square is congruent module $1$ or $4$ to 5, which is essentially the same statement. Clearly, any integer which has $3$ as its last digit is congruent modulo $3$, which is a contradiction. PS: integers which are multiples of $10$ end with a $0$ (in fact, two of them), but I assume you aren't considering squares of $0$ when you look at $mathbb Z_5$.
edited Nov 30 '18 at 5:39
answered Nov 30 '18 at 2:52
BoshuBoshu
705315
705315
add a comment |
add a comment |
You yourself wrote down
For each integer a,if a≆0 (mod 5),then a^2≅1(mod 5) or a^2≅4(mod 5)
Does $a^2 = 5,158,232,468,953,153$ satisfy those conditions?
However you have to consider that maybe $a cong 0 pmod 5$. In which case $a^2 cong 0 pmod 5$. Do $a^2$ satisfy that condition either?
No, because either way, the number doesn't end in a 0 or a 5, so it's not divisible by 5. The 0 condition isn't satisified either because perfect squares only end in 1, 4, 6, or 9
– Claire
Nov 30 '18 at 2:59
Is this the reason why it's not true then? @fleablood
– Claire
Nov 30 '18 at 3:18
Well, you DID say $a^2$ must be equiv $1$ or $4$ mod $5$. Or $a$ equiv $0$. And $5,1....,.53$ is not that. So you tell me. Is it possible for something to happen that you yourself proved could not happen?
– fleablood
Nov 30 '18 at 4:27
But perfect squares like 100, 400, 900, 1600, etc. can and with $0$.
– fleablood
Nov 30 '18 at 4:28
add a comment |
You yourself wrote down
For each integer a,if a≆0 (mod 5),then a^2≅1(mod 5) or a^2≅4(mod 5)
Does $a^2 = 5,158,232,468,953,153$ satisfy those conditions?
However you have to consider that maybe $a cong 0 pmod 5$. In which case $a^2 cong 0 pmod 5$. Do $a^2$ satisfy that condition either?
No, because either way, the number doesn't end in a 0 or a 5, so it's not divisible by 5. The 0 condition isn't satisified either because perfect squares only end in 1, 4, 6, or 9
– Claire
Nov 30 '18 at 2:59
Is this the reason why it's not true then? @fleablood
– Claire
Nov 30 '18 at 3:18
Well, you DID say $a^2$ must be equiv $1$ or $4$ mod $5$. Or $a$ equiv $0$. And $5,1....,.53$ is not that. So you tell me. Is it possible for something to happen that you yourself proved could not happen?
– fleablood
Nov 30 '18 at 4:27
But perfect squares like 100, 400, 900, 1600, etc. can and with $0$.
– fleablood
Nov 30 '18 at 4:28
add a comment |
You yourself wrote down
For each integer a,if a≆0 (mod 5),then a^2≅1(mod 5) or a^2≅4(mod 5)
Does $a^2 = 5,158,232,468,953,153$ satisfy those conditions?
However you have to consider that maybe $a cong 0 pmod 5$. In which case $a^2 cong 0 pmod 5$. Do $a^2$ satisfy that condition either?
You yourself wrote down
For each integer a,if a≆0 (mod 5),then a^2≅1(mod 5) or a^2≅4(mod 5)
Does $a^2 = 5,158,232,468,953,153$ satisfy those conditions?
However you have to consider that maybe $a cong 0 pmod 5$. In which case $a^2 cong 0 pmod 5$. Do $a^2$ satisfy that condition either?
answered Nov 30 '18 at 2:57
fleabloodfleablood
68.7k22685
68.7k22685
No, because either way, the number doesn't end in a 0 or a 5, so it's not divisible by 5. The 0 condition isn't satisified either because perfect squares only end in 1, 4, 6, or 9
– Claire
Nov 30 '18 at 2:59
Is this the reason why it's not true then? @fleablood
– Claire
Nov 30 '18 at 3:18
Well, you DID say $a^2$ must be equiv $1$ or $4$ mod $5$. Or $a$ equiv $0$. And $5,1....,.53$ is not that. So you tell me. Is it possible for something to happen that you yourself proved could not happen?
– fleablood
Nov 30 '18 at 4:27
But perfect squares like 100, 400, 900, 1600, etc. can and with $0$.
– fleablood
Nov 30 '18 at 4:28
add a comment |
No, because either way, the number doesn't end in a 0 or a 5, so it's not divisible by 5. The 0 condition isn't satisified either because perfect squares only end in 1, 4, 6, or 9
– Claire
Nov 30 '18 at 2:59
Is this the reason why it's not true then? @fleablood
– Claire
Nov 30 '18 at 3:18
Well, you DID say $a^2$ must be equiv $1$ or $4$ mod $5$. Or $a$ equiv $0$. And $5,1....,.53$ is not that. So you tell me. Is it possible for something to happen that you yourself proved could not happen?
– fleablood
Nov 30 '18 at 4:27
But perfect squares like 100, 400, 900, 1600, etc. can and with $0$.
– fleablood
Nov 30 '18 at 4:28
No, because either way, the number doesn't end in a 0 or a 5, so it's not divisible by 5. The 0 condition isn't satisified either because perfect squares only end in 1, 4, 6, or 9
– Claire
Nov 30 '18 at 2:59
No, because either way, the number doesn't end in a 0 or a 5, so it's not divisible by 5. The 0 condition isn't satisified either because perfect squares only end in 1, 4, 6, or 9
– Claire
Nov 30 '18 at 2:59
Is this the reason why it's not true then? @fleablood
– Claire
Nov 30 '18 at 3:18
Is this the reason why it's not true then? @fleablood
– Claire
Nov 30 '18 at 3:18
Well, you DID say $a^2$ must be equiv $1$ or $4$ mod $5$. Or $a$ equiv $0$. And $5,1....,.53$ is not that. So you tell me. Is it possible for something to happen that you yourself proved could not happen?
– fleablood
Nov 30 '18 at 4:27
Well, you DID say $a^2$ must be equiv $1$ or $4$ mod $5$. Or $a$ equiv $0$. And $5,1....,.53$ is not that. So you tell me. Is it possible for something to happen that you yourself proved could not happen?
– fleablood
Nov 30 '18 at 4:27
But perfect squares like 100, 400, 900, 1600, etc. can and with $0$.
– fleablood
Nov 30 '18 at 4:28
But perfect squares like 100, 400, 900, 1600, etc. can and with $0$.
– fleablood
Nov 30 '18 at 4:28
add a comment |
Thanks for contributing an answer to Mathematics Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3019548%2fdoes-there-exist-a-in-mathbb-z-such-that-a2-5-158-232-468-953-153%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Well, if such an $a$ existed then $a^2$ is $3$ modulo $5$. Do you see the problem?
– T. Bongers
Nov 30 '18 at 2:46
where did you get the 3 from ? @T.Bongers
– Claire
Nov 30 '18 at 2:51
@Claire you number $5,158,232,468,953,153$ end with digit $3$.
– achille hui
Nov 30 '18 at 2:53
Is $5,158,232,468,953,153cong 1,4 pmod 5$?
– fleablood
Nov 30 '18 at 2:53
can any square number have 3 as the last digit.
– karakfa
Nov 30 '18 at 2:53