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Number multiplied by itself does not give a square number


Are square numbers also known as rectangular numbers, too?I call them squares. They called them arrays. What do they mean?When is $8x^2-4$ a square number?A property regarding complete/perfect squares.If the square of a natural number is odd then this number is odd.Can a multi-perfect number be a perfect square?What is the series of numbers, where each number is a triangular, square, and hexagonal number?Why is there a pattern to the last digits of square numbers?Is mean squared error equivalent to mean squared absolute errorThree-Digit Square Containing Numbers 1-9













1












$begingroup$


The answer to this is probably very simple but while working on a question I was surprised to discover than a number multiplied by itself does not give the same answer as the same number squared (in the case of negative numbers).



Examples:



$-1^2 = -1$



If I now multiply this number by itself $-1 * -1$ I get $1$



$-4^2 = -16$



$-4 * -4 = 16$



The same goes for all the other negative numbers I tried.



What changes when squaring a number and how do I understand what is going on? When I multiply a positive number by itself I get a square number, why does this not work with negative numbers?










share|cite|improve this question









$endgroup$







  • 4




    $begingroup$
    It's just operator precedence. $-x^2$ does not mean $(-x)^2$, it means $-(x^2)$.
    $endgroup$
    – Robert Israel
    Mar 14 at 16:49










  • $begingroup$
    What you've done above is not squaring a number. It is true (depending on how you interpret order of operations) that $-1^2=-1$. But what you are actually asking about is $(-1)^2$ which is exactly $1$. By definition, $x^2$ is the same thing as $xcdot x$.
    $endgroup$
    – Nick Peterson
    Mar 14 at 16:50










  • $begingroup$
    @NickPeterson So it's actually (-1)1^2
    $endgroup$
    – Simon
    Mar 14 at 16:55










  • $begingroup$
    @Robert Israel thank you I understand now
    $endgroup$
    – Simon
    Mar 14 at 16:56















1












$begingroup$


The answer to this is probably very simple but while working on a question I was surprised to discover than a number multiplied by itself does not give the same answer as the same number squared (in the case of negative numbers).



Examples:



$-1^2 = -1$



If I now multiply this number by itself $-1 * -1$ I get $1$



$-4^2 = -16$



$-4 * -4 = 16$



The same goes for all the other negative numbers I tried.



What changes when squaring a number and how do I understand what is going on? When I multiply a positive number by itself I get a square number, why does this not work with negative numbers?










share|cite|improve this question









$endgroup$







  • 4




    $begingroup$
    It's just operator precedence. $-x^2$ does not mean $(-x)^2$, it means $-(x^2)$.
    $endgroup$
    – Robert Israel
    Mar 14 at 16:49










  • $begingroup$
    What you've done above is not squaring a number. It is true (depending on how you interpret order of operations) that $-1^2=-1$. But what you are actually asking about is $(-1)^2$ which is exactly $1$. By definition, $x^2$ is the same thing as $xcdot x$.
    $endgroup$
    – Nick Peterson
    Mar 14 at 16:50










  • $begingroup$
    @NickPeterson So it's actually (-1)1^2
    $endgroup$
    – Simon
    Mar 14 at 16:55










  • $begingroup$
    @Robert Israel thank you I understand now
    $endgroup$
    – Simon
    Mar 14 at 16:56













1












1








1





$begingroup$


The answer to this is probably very simple but while working on a question I was surprised to discover than a number multiplied by itself does not give the same answer as the same number squared (in the case of negative numbers).



Examples:



$-1^2 = -1$



If I now multiply this number by itself $-1 * -1$ I get $1$



$-4^2 = -16$



$-4 * -4 = 16$



The same goes for all the other negative numbers I tried.



What changes when squaring a number and how do I understand what is going on? When I multiply a positive number by itself I get a square number, why does this not work with negative numbers?










share|cite|improve this question









$endgroup$




The answer to this is probably very simple but while working on a question I was surprised to discover than a number multiplied by itself does not give the same answer as the same number squared (in the case of negative numbers).



Examples:



$-1^2 = -1$



If I now multiply this number by itself $-1 * -1$ I get $1$



$-4^2 = -16$



$-4 * -4 = 16$



The same goes for all the other negative numbers I tried.



What changes when squaring a number and how do I understand what is going on? When I multiply a positive number by itself I get a square number, why does this not work with negative numbers?







square-numbers






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Mar 14 at 16:47









SimonSimon

1104




1104







  • 4




    $begingroup$
    It's just operator precedence. $-x^2$ does not mean $(-x)^2$, it means $-(x^2)$.
    $endgroup$
    – Robert Israel
    Mar 14 at 16:49










  • $begingroup$
    What you've done above is not squaring a number. It is true (depending on how you interpret order of operations) that $-1^2=-1$. But what you are actually asking about is $(-1)^2$ which is exactly $1$. By definition, $x^2$ is the same thing as $xcdot x$.
    $endgroup$
    – Nick Peterson
    Mar 14 at 16:50










  • $begingroup$
    @NickPeterson So it's actually (-1)1^2
    $endgroup$
    – Simon
    Mar 14 at 16:55










  • $begingroup$
    @Robert Israel thank you I understand now
    $endgroup$
    – Simon
    Mar 14 at 16:56












  • 4




    $begingroup$
    It's just operator precedence. $-x^2$ does not mean $(-x)^2$, it means $-(x^2)$.
    $endgroup$
    – Robert Israel
    Mar 14 at 16:49










  • $begingroup$
    What you've done above is not squaring a number. It is true (depending on how you interpret order of operations) that $-1^2=-1$. But what you are actually asking about is $(-1)^2$ which is exactly $1$. By definition, $x^2$ is the same thing as $xcdot x$.
    $endgroup$
    – Nick Peterson
    Mar 14 at 16:50










  • $begingroup$
    @NickPeterson So it's actually (-1)1^2
    $endgroup$
    – Simon
    Mar 14 at 16:55










  • $begingroup$
    @Robert Israel thank you I understand now
    $endgroup$
    – Simon
    Mar 14 at 16:56







4




4




$begingroup$
It's just operator precedence. $-x^2$ does not mean $(-x)^2$, it means $-(x^2)$.
$endgroup$
– Robert Israel
Mar 14 at 16:49




$begingroup$
It's just operator precedence. $-x^2$ does not mean $(-x)^2$, it means $-(x^2)$.
$endgroup$
– Robert Israel
Mar 14 at 16:49












$begingroup$
What you've done above is not squaring a number. It is true (depending on how you interpret order of operations) that $-1^2=-1$. But what you are actually asking about is $(-1)^2$ which is exactly $1$. By definition, $x^2$ is the same thing as $xcdot x$.
$endgroup$
– Nick Peterson
Mar 14 at 16:50




$begingroup$
What you've done above is not squaring a number. It is true (depending on how you interpret order of operations) that $-1^2=-1$. But what you are actually asking about is $(-1)^2$ which is exactly $1$. By definition, $x^2$ is the same thing as $xcdot x$.
$endgroup$
– Nick Peterson
Mar 14 at 16:50












$begingroup$
@NickPeterson So it's actually (-1)1^2
$endgroup$
– Simon
Mar 14 at 16:55




$begingroup$
@NickPeterson So it's actually (-1)1^2
$endgroup$
– Simon
Mar 14 at 16:55












$begingroup$
@Robert Israel thank you I understand now
$endgroup$
– Simon
Mar 14 at 16:56




$begingroup$
@Robert Israel thank you I understand now
$endgroup$
– Simon
Mar 14 at 16:56










1 Answer
1






active

oldest

votes


















1












$begingroup$

Note that the square of $-1$ is $$ (-1)^2 = (-1)times (-1) = 1 ne -1 .$$ You've mixed up operator precedence by putting $$ -(1)^2 = - (1) times (1) = - 1 . $$



In general $-(x)^2$ is $- (xcdot x)$, because exponentiation has a higher operator precedence than negation. You can read more about the order of operations here.






share|cite|improve this answer









$endgroup$












  • $begingroup$
    I see I understand now. I'll accept your answer. Thank you, it was as obvious as I expected
    $endgroup$
    – Simon
    Mar 14 at 16:59










Your Answer





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1 Answer
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active

oldest

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active

oldest

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active

oldest

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1












$begingroup$

Note that the square of $-1$ is $$ (-1)^2 = (-1)times (-1) = 1 ne -1 .$$ You've mixed up operator precedence by putting $$ -(1)^2 = - (1) times (1) = - 1 . $$



In general $-(x)^2$ is $- (xcdot x)$, because exponentiation has a higher operator precedence than negation. You can read more about the order of operations here.






share|cite|improve this answer









$endgroup$












  • $begingroup$
    I see I understand now. I'll accept your answer. Thank you, it was as obvious as I expected
    $endgroup$
    – Simon
    Mar 14 at 16:59















1












$begingroup$

Note that the square of $-1$ is $$ (-1)^2 = (-1)times (-1) = 1 ne -1 .$$ You've mixed up operator precedence by putting $$ -(1)^2 = - (1) times (1) = - 1 . $$



In general $-(x)^2$ is $- (xcdot x)$, because exponentiation has a higher operator precedence than negation. You can read more about the order of operations here.






share|cite|improve this answer









$endgroup$












  • $begingroup$
    I see I understand now. I'll accept your answer. Thank you, it was as obvious as I expected
    $endgroup$
    – Simon
    Mar 14 at 16:59













1












1








1





$begingroup$

Note that the square of $-1$ is $$ (-1)^2 = (-1)times (-1) = 1 ne -1 .$$ You've mixed up operator precedence by putting $$ -(1)^2 = - (1) times (1) = - 1 . $$



In general $-(x)^2$ is $- (xcdot x)$, because exponentiation has a higher operator precedence than negation. You can read more about the order of operations here.






share|cite|improve this answer









$endgroup$



Note that the square of $-1$ is $$ (-1)^2 = (-1)times (-1) = 1 ne -1 .$$ You've mixed up operator precedence by putting $$ -(1)^2 = - (1) times (1) = - 1 . $$



In general $-(x)^2$ is $- (xcdot x)$, because exponentiation has a higher operator precedence than negation. You can read more about the order of operations here.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Mar 14 at 16:53









Dando18Dando18

4,73241235




4,73241235











  • $begingroup$
    I see I understand now. I'll accept your answer. Thank you, it was as obvious as I expected
    $endgroup$
    – Simon
    Mar 14 at 16:59
















  • $begingroup$
    I see I understand now. I'll accept your answer. Thank you, it was as obvious as I expected
    $endgroup$
    – Simon
    Mar 14 at 16:59















$begingroup$
I see I understand now. I'll accept your answer. Thank you, it was as obvious as I expected
$endgroup$
– Simon
Mar 14 at 16:59




$begingroup$
I see I understand now. I'll accept your answer. Thank you, it was as obvious as I expected
$endgroup$
– Simon
Mar 14 at 16:59

















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