Neutral Element on $(mathbb{C},*,+)$











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I want to show the neutral Element on $$(mathbb{C},*,+)$$



Let the complex Number be defined as:
$$(x,y)$$
Multiplication of complex numbers is defined as:
$$(x_{1}, y_{1}) * (x_{2}, y_{2}):= (x_{1}x_{2}-y_{1}y_{2}, x_{1}y_{2}+x_{2}y_{1})$$
By definition the neutral element is:
$$(e_{x}, e_{y}) *(x,y) = (x,y)$$
$$(x*e_{x}-y*e_{y}, x*e_{y}+y*e_{x})$$
This gives an equation system:
$$x = x*e_{x} -y*e_{y}$$
$$y = x*e_{y} +y*e_{x}$$



Is this the correct approach to finding the neutral Element?



If yes, what is the correct method for solving the equation system?










share|cite|improve this question
























  • Of course you can determine the multplicative neutral element by solving the above equation system. But I am sure you already know that the neutral element is $(1,0)$, and in that case it suffices to verify the equation $(1,0) * (x,y) = (x,y)$.
    – Paul Frost
    23 hours ago










  • I want to show how to get to the value (1,0)
    – Thomas Christopher Davies
    19 hours ago










  • Then simply note that you must have $(e_x,e_y) * (1,0) = (1,0)$. This gives you $1 = e_x$ and $0 = e_y$.
    – Paul Frost
    19 hours ago










  • I don't see this being a good derivation
    – Thomas Christopher Davies
    18 hours ago















up vote
0
down vote

favorite












I want to show the neutral Element on $$(mathbb{C},*,+)$$



Let the complex Number be defined as:
$$(x,y)$$
Multiplication of complex numbers is defined as:
$$(x_{1}, y_{1}) * (x_{2}, y_{2}):= (x_{1}x_{2}-y_{1}y_{2}, x_{1}y_{2}+x_{2}y_{1})$$
By definition the neutral element is:
$$(e_{x}, e_{y}) *(x,y) = (x,y)$$
$$(x*e_{x}-y*e_{y}, x*e_{y}+y*e_{x})$$
This gives an equation system:
$$x = x*e_{x} -y*e_{y}$$
$$y = x*e_{y} +y*e_{x}$$



Is this the correct approach to finding the neutral Element?



If yes, what is the correct method for solving the equation system?










share|cite|improve this question
























  • Of course you can determine the multplicative neutral element by solving the above equation system. But I am sure you already know that the neutral element is $(1,0)$, and in that case it suffices to verify the equation $(1,0) * (x,y) = (x,y)$.
    – Paul Frost
    23 hours ago










  • I want to show how to get to the value (1,0)
    – Thomas Christopher Davies
    19 hours ago










  • Then simply note that you must have $(e_x,e_y) * (1,0) = (1,0)$. This gives you $1 = e_x$ and $0 = e_y$.
    – Paul Frost
    19 hours ago










  • I don't see this being a good derivation
    – Thomas Christopher Davies
    18 hours ago













up vote
0
down vote

favorite









up vote
0
down vote

favorite











I want to show the neutral Element on $$(mathbb{C},*,+)$$



Let the complex Number be defined as:
$$(x,y)$$
Multiplication of complex numbers is defined as:
$$(x_{1}, y_{1}) * (x_{2}, y_{2}):= (x_{1}x_{2}-y_{1}y_{2}, x_{1}y_{2}+x_{2}y_{1})$$
By definition the neutral element is:
$$(e_{x}, e_{y}) *(x,y) = (x,y)$$
$$(x*e_{x}-y*e_{y}, x*e_{y}+y*e_{x})$$
This gives an equation system:
$$x = x*e_{x} -y*e_{y}$$
$$y = x*e_{y} +y*e_{x}$$



Is this the correct approach to finding the neutral Element?



If yes, what is the correct method for solving the equation system?










share|cite|improve this question















I want to show the neutral Element on $$(mathbb{C},*,+)$$



Let the complex Number be defined as:
$$(x,y)$$
Multiplication of complex numbers is defined as:
$$(x_{1}, y_{1}) * (x_{2}, y_{2}):= (x_{1}x_{2}-y_{1}y_{2}, x_{1}y_{2}+x_{2}y_{1})$$
By definition the neutral element is:
$$(e_{x}, e_{y}) *(x,y) = (x,y)$$
$$(x*e_{x}-y*e_{y}, x*e_{y}+y*e_{x})$$
This gives an equation system:
$$x = x*e_{x} -y*e_{y}$$
$$y = x*e_{y} +y*e_{x}$$



Is this the correct approach to finding the neutral Element?



If yes, what is the correct method for solving the equation system?







complex-numbers systems-of-equations






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited 23 hours ago









Cameron Buie

84.4k771155




84.4k771155










asked 23 hours ago









Thomas Christopher Davies

247




247












  • Of course you can determine the multplicative neutral element by solving the above equation system. But I am sure you already know that the neutral element is $(1,0)$, and in that case it suffices to verify the equation $(1,0) * (x,y) = (x,y)$.
    – Paul Frost
    23 hours ago










  • I want to show how to get to the value (1,0)
    – Thomas Christopher Davies
    19 hours ago










  • Then simply note that you must have $(e_x,e_y) * (1,0) = (1,0)$. This gives you $1 = e_x$ and $0 = e_y$.
    – Paul Frost
    19 hours ago










  • I don't see this being a good derivation
    – Thomas Christopher Davies
    18 hours ago


















  • Of course you can determine the multplicative neutral element by solving the above equation system. But I am sure you already know that the neutral element is $(1,0)$, and in that case it suffices to verify the equation $(1,0) * (x,y) = (x,y)$.
    – Paul Frost
    23 hours ago










  • I want to show how to get to the value (1,0)
    – Thomas Christopher Davies
    19 hours ago










  • Then simply note that you must have $(e_x,e_y) * (1,0) = (1,0)$. This gives you $1 = e_x$ and $0 = e_y$.
    – Paul Frost
    19 hours ago










  • I don't see this being a good derivation
    – Thomas Christopher Davies
    18 hours ago
















Of course you can determine the multplicative neutral element by solving the above equation system. But I am sure you already know that the neutral element is $(1,0)$, and in that case it suffices to verify the equation $(1,0) * (x,y) = (x,y)$.
– Paul Frost
23 hours ago




Of course you can determine the multplicative neutral element by solving the above equation system. But I am sure you already know that the neutral element is $(1,0)$, and in that case it suffices to verify the equation $(1,0) * (x,y) = (x,y)$.
– Paul Frost
23 hours ago












I want to show how to get to the value (1,0)
– Thomas Christopher Davies
19 hours ago




I want to show how to get to the value (1,0)
– Thomas Christopher Davies
19 hours ago












Then simply note that you must have $(e_x,e_y) * (1,0) = (1,0)$. This gives you $1 = e_x$ and $0 = e_y$.
– Paul Frost
19 hours ago




Then simply note that you must have $(e_x,e_y) * (1,0) = (1,0)$. This gives you $1 = e_x$ and $0 = e_y$.
– Paul Frost
19 hours ago












I don't see this being a good derivation
– Thomas Christopher Davies
18 hours ago




I don't see this being a good derivation
– Thomas Christopher Davies
18 hours ago










1 Answer
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up vote
2
down vote













Your approach is not (quite) correct because you should have $x=xe_x-ye_y$ and $y=xe_y+ye_x$ (just normal multiplication instead of your "*" operation). Also, the equations should hold for any x and y in $mathbb{C}$ and this implies that $e_x=1$ and $e_y=0$






share|cite|improve this answer





















  • But how can I show it?
    – Thomas Christopher Davies
    19 hours ago










  • @Thomas Cristopher Davies : Your mistake is that you are confusing “” with the normal multiplication between two real numbers. Your operation is defined so that ($e_x,e_y$)(x,y)= ($e_xx-e_yy,e_xy+e_yx$) and NOT as ($e_x,e_y$)(x,y)= ($e_x*x-e_y*y,e_x*y+e_y*x$). It wouldn’t even make sens for “” to be defined in terms of itself...by the way, “*” is just complex multiplication
    – Sorin Tirc
    15 hours ago













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1 Answer
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1 Answer
1






active

oldest

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oldest

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oldest

votes








up vote
2
down vote













Your approach is not (quite) correct because you should have $x=xe_x-ye_y$ and $y=xe_y+ye_x$ (just normal multiplication instead of your "*" operation). Also, the equations should hold for any x and y in $mathbb{C}$ and this implies that $e_x=1$ and $e_y=0$






share|cite|improve this answer





















  • But how can I show it?
    – Thomas Christopher Davies
    19 hours ago










  • @Thomas Cristopher Davies : Your mistake is that you are confusing “” with the normal multiplication between two real numbers. Your operation is defined so that ($e_x,e_y$)(x,y)= ($e_xx-e_yy,e_xy+e_yx$) and NOT as ($e_x,e_y$)(x,y)= ($e_x*x-e_y*y,e_x*y+e_y*x$). It wouldn’t even make sens for “” to be defined in terms of itself...by the way, “*” is just complex multiplication
    – Sorin Tirc
    15 hours ago

















up vote
2
down vote













Your approach is not (quite) correct because you should have $x=xe_x-ye_y$ and $y=xe_y+ye_x$ (just normal multiplication instead of your "*" operation). Also, the equations should hold for any x and y in $mathbb{C}$ and this implies that $e_x=1$ and $e_y=0$






share|cite|improve this answer





















  • But how can I show it?
    – Thomas Christopher Davies
    19 hours ago










  • @Thomas Cristopher Davies : Your mistake is that you are confusing “” with the normal multiplication between two real numbers. Your operation is defined so that ($e_x,e_y$)(x,y)= ($e_xx-e_yy,e_xy+e_yx$) and NOT as ($e_x,e_y$)(x,y)= ($e_x*x-e_y*y,e_x*y+e_y*x$). It wouldn’t even make sens for “” to be defined in terms of itself...by the way, “*” is just complex multiplication
    – Sorin Tirc
    15 hours ago















up vote
2
down vote










up vote
2
down vote









Your approach is not (quite) correct because you should have $x=xe_x-ye_y$ and $y=xe_y+ye_x$ (just normal multiplication instead of your "*" operation). Also, the equations should hold for any x and y in $mathbb{C}$ and this implies that $e_x=1$ and $e_y=0$






share|cite|improve this answer












Your approach is not (quite) correct because you should have $x=xe_x-ye_y$ and $y=xe_y+ye_x$ (just normal multiplication instead of your "*" operation). Also, the equations should hold for any x and y in $mathbb{C}$ and this implies that $e_x=1$ and $e_y=0$







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered 23 hours ago









Sorin Tirc

4888




4888












  • But how can I show it?
    – Thomas Christopher Davies
    19 hours ago










  • @Thomas Cristopher Davies : Your mistake is that you are confusing “” with the normal multiplication between two real numbers. Your operation is defined so that ($e_x,e_y$)(x,y)= ($e_xx-e_yy,e_xy+e_yx$) and NOT as ($e_x,e_y$)(x,y)= ($e_x*x-e_y*y,e_x*y+e_y*x$). It wouldn’t even make sens for “” to be defined in terms of itself...by the way, “*” is just complex multiplication
    – Sorin Tirc
    15 hours ago




















  • But how can I show it?
    – Thomas Christopher Davies
    19 hours ago










  • @Thomas Cristopher Davies : Your mistake is that you are confusing “” with the normal multiplication between two real numbers. Your operation is defined so that ($e_x,e_y$)(x,y)= ($e_xx-e_yy,e_xy+e_yx$) and NOT as ($e_x,e_y$)(x,y)= ($e_x*x-e_y*y,e_x*y+e_y*x$). It wouldn’t even make sens for “” to be defined in terms of itself...by the way, “*” is just complex multiplication
    – Sorin Tirc
    15 hours ago


















But how can I show it?
– Thomas Christopher Davies
19 hours ago




But how can I show it?
– Thomas Christopher Davies
19 hours ago












@Thomas Cristopher Davies : Your mistake is that you are confusing “” with the normal multiplication between two real numbers. Your operation is defined so that ($e_x,e_y$)(x,y)= ($e_xx-e_yy,e_xy+e_yx$) and NOT as ($e_x,e_y$)(x,y)= ($e_x*x-e_y*y,e_x*y+e_y*x$). It wouldn’t even make sens for “” to be defined in terms of itself...by the way, “*” is just complex multiplication
– Sorin Tirc
15 hours ago






@Thomas Cristopher Davies : Your mistake is that you are confusing “” with the normal multiplication between two real numbers. Your operation is defined so that ($e_x,e_y$)(x,y)= ($e_xx-e_yy,e_xy+e_yx$) and NOT as ($e_x,e_y$)(x,y)= ($e_x*x-e_y*y,e_x*y+e_y*x$). It wouldn’t even make sens for “” to be defined in terms of itself...by the way, “*” is just complex multiplication
– Sorin Tirc
15 hours ago




















 

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