A question on Complex numbers.
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If $$z=dfrac{sqrt{3}-i}{2}$$ then $$(z^{95}+i^{67})^{94}=z^n$$ then, $text{find the smallest positive integral value of}$ $n$ $text{where}$ $i=sqrt{-1}$
$text{My Attempt:}$ First of all I tried to convert $z$ into $text{Euler's Form}$ so, $z=e^{-i(frac{π}{6})}$
Then, I raised $z$ to the $text{95th}$ power. Then I'm getting stuck. And, not being able to proceed. Help.
complex-numbers
$endgroup$
add a comment |
$begingroup$
If $$z=dfrac{sqrt{3}-i}{2}$$ then $$(z^{95}+i^{67})^{94}=z^n$$ then, $text{find the smallest positive integral value of}$ $n$ $text{where}$ $i=sqrt{-1}$
$text{My Attempt:}$ First of all I tried to convert $z$ into $text{Euler's Form}$ so, $z=e^{-i(frac{π}{6})}$
Then, I raised $z$ to the $text{95th}$ power. Then I'm getting stuck. And, not being able to proceed. Help.
complex-numbers
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$begingroup$
You can use that $e^{2pi i}=1$, from that $z^{95}$ can be expressed as $e^{ix}$ for $x$ in $[0,2pi)$, what is this $x$?
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– lEm
Jan 8 at 5:08
1
$begingroup$
Hello: for future reference, it is always a bad choice to title your question "question on <subject area>". It would be better to copy your actual question into the title, at that rate, since it fits.
$endgroup$
– rschwieb
Jan 8 at 14:48
add a comment |
$begingroup$
If $$z=dfrac{sqrt{3}-i}{2}$$ then $$(z^{95}+i^{67})^{94}=z^n$$ then, $text{find the smallest positive integral value of}$ $n$ $text{where}$ $i=sqrt{-1}$
$text{My Attempt:}$ First of all I tried to convert $z$ into $text{Euler's Form}$ so, $z=e^{-i(frac{π}{6})}$
Then, I raised $z$ to the $text{95th}$ power. Then I'm getting stuck. And, not being able to proceed. Help.
complex-numbers
$endgroup$
If $$z=dfrac{sqrt{3}-i}{2}$$ then $$(z^{95}+i^{67})^{94}=z^n$$ then, $text{find the smallest positive integral value of}$ $n$ $text{where}$ $i=sqrt{-1}$
$text{My Attempt:}$ First of all I tried to convert $z$ into $text{Euler's Form}$ so, $z=e^{-i(frac{π}{6})}$
Then, I raised $z$ to the $text{95th}$ power. Then I'm getting stuck. And, not being able to proceed. Help.
complex-numbers
complex-numbers
edited Jan 8 at 5:55
Pritam Acharya
asked Jan 8 at 5:01
Pritam AcharyaPritam Acharya
828
828
$begingroup$
You can use that $e^{2pi i}=1$, from that $z^{95}$ can be expressed as $e^{ix}$ for $x$ in $[0,2pi)$, what is this $x$?
$endgroup$
– lEm
Jan 8 at 5:08
1
$begingroup$
Hello: for future reference, it is always a bad choice to title your question "question on <subject area>". It would be better to copy your actual question into the title, at that rate, since it fits.
$endgroup$
– rschwieb
Jan 8 at 14:48
add a comment |
$begingroup$
You can use that $e^{2pi i}=1$, from that $z^{95}$ can be expressed as $e^{ix}$ for $x$ in $[0,2pi)$, what is this $x$?
$endgroup$
– lEm
Jan 8 at 5:08
1
$begingroup$
Hello: for future reference, it is always a bad choice to title your question "question on <subject area>". It would be better to copy your actual question into the title, at that rate, since it fits.
$endgroup$
– rschwieb
Jan 8 at 14:48
$begingroup$
You can use that $e^{2pi i}=1$, from that $z^{95}$ can be expressed as $e^{ix}$ for $x$ in $[0,2pi)$, what is this $x$?
$endgroup$
– lEm
Jan 8 at 5:08
$begingroup$
You can use that $e^{2pi i}=1$, from that $z^{95}$ can be expressed as $e^{ix}$ for $x$ in $[0,2pi)$, what is this $x$?
$endgroup$
– lEm
Jan 8 at 5:08
1
1
$begingroup$
Hello: for future reference, it is always a bad choice to title your question "question on <subject area>". It would be better to copy your actual question into the title, at that rate, since it fits.
$endgroup$
– rschwieb
Jan 8 at 14:48
$begingroup$
Hello: for future reference, it is always a bad choice to title your question "question on <subject area>". It would be better to copy your actual question into the title, at that rate, since it fits.
$endgroup$
– rschwieb
Jan 8 at 14:48
add a comment |
2 Answers
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oldest
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$begingroup$
$$z=e^{-ipi/6}implies z^{95}=e^{-95ipi/6}=e^{-16ipi+ipi/6}=e^{ipi/6}\i^{67}=i^{64}(-i)=-i$$So we have $$z^{95}+i^{67}=e^{ipi/6}+e^{-ipi/2}=frac{sqrt3+i}{2}-i=frac{sqrt{3}-i}2=z$$
$$z^{94}=z^{-2}=z^{10}$$So the smallest positive integer for which $(z^{95}+i^{67})^{94}=z^n$ is $n=10$.
$endgroup$
add a comment |
$begingroup$
$z^6=-1$
$z^{12m-1}=z^{-1}=e^{ipi/6}$
$i^{4n+3}=i^3=-i$
$z^{12m-1}+i^{4n+3}=$cis$(pi/6)-i=$cis$(-pi/6)=z$
where cis $=cos +isin$
So, we have $z^{n-94}=1$
$implies12$ divides $n-94$
$endgroup$
add a comment |
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2 Answers
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2 Answers
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$begingroup$
$$z=e^{-ipi/6}implies z^{95}=e^{-95ipi/6}=e^{-16ipi+ipi/6}=e^{ipi/6}\i^{67}=i^{64}(-i)=-i$$So we have $$z^{95}+i^{67}=e^{ipi/6}+e^{-ipi/2}=frac{sqrt3+i}{2}-i=frac{sqrt{3}-i}2=z$$
$$z^{94}=z^{-2}=z^{10}$$So the smallest positive integer for which $(z^{95}+i^{67})^{94}=z^n$ is $n=10$.
$endgroup$
add a comment |
$begingroup$
$$z=e^{-ipi/6}implies z^{95}=e^{-95ipi/6}=e^{-16ipi+ipi/6}=e^{ipi/6}\i^{67}=i^{64}(-i)=-i$$So we have $$z^{95}+i^{67}=e^{ipi/6}+e^{-ipi/2}=frac{sqrt3+i}{2}-i=frac{sqrt{3}-i}2=z$$
$$z^{94}=z^{-2}=z^{10}$$So the smallest positive integer for which $(z^{95}+i^{67})^{94}=z^n$ is $n=10$.
$endgroup$
add a comment |
$begingroup$
$$z=e^{-ipi/6}implies z^{95}=e^{-95ipi/6}=e^{-16ipi+ipi/6}=e^{ipi/6}\i^{67}=i^{64}(-i)=-i$$So we have $$z^{95}+i^{67}=e^{ipi/6}+e^{-ipi/2}=frac{sqrt3+i}{2}-i=frac{sqrt{3}-i}2=z$$
$$z^{94}=z^{-2}=z^{10}$$So the smallest positive integer for which $(z^{95}+i^{67})^{94}=z^n$ is $n=10$.
$endgroup$
$$z=e^{-ipi/6}implies z^{95}=e^{-95ipi/6}=e^{-16ipi+ipi/6}=e^{ipi/6}\i^{67}=i^{64}(-i)=-i$$So we have $$z^{95}+i^{67}=e^{ipi/6}+e^{-ipi/2}=frac{sqrt3+i}{2}-i=frac{sqrt{3}-i}2=z$$
$$z^{94}=z^{-2}=z^{10}$$So the smallest positive integer for which $(z^{95}+i^{67})^{94}=z^n$ is $n=10$.
answered Jan 8 at 5:14
John DoeJohn Doe
12.1k11339
12.1k11339
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$begingroup$
$z^6=-1$
$z^{12m-1}=z^{-1}=e^{ipi/6}$
$i^{4n+3}=i^3=-i$
$z^{12m-1}+i^{4n+3}=$cis$(pi/6)-i=$cis$(-pi/6)=z$
where cis $=cos +isin$
So, we have $z^{n-94}=1$
$implies12$ divides $n-94$
$endgroup$
add a comment |
$begingroup$
$z^6=-1$
$z^{12m-1}=z^{-1}=e^{ipi/6}$
$i^{4n+3}=i^3=-i$
$z^{12m-1}+i^{4n+3}=$cis$(pi/6)-i=$cis$(-pi/6)=z$
where cis $=cos +isin$
So, we have $z^{n-94}=1$
$implies12$ divides $n-94$
$endgroup$
add a comment |
$begingroup$
$z^6=-1$
$z^{12m-1}=z^{-1}=e^{ipi/6}$
$i^{4n+3}=i^3=-i$
$z^{12m-1}+i^{4n+3}=$cis$(pi/6)-i=$cis$(-pi/6)=z$
where cis $=cos +isin$
So, we have $z^{n-94}=1$
$implies12$ divides $n-94$
$endgroup$
$z^6=-1$
$z^{12m-1}=z^{-1}=e^{ipi/6}$
$i^{4n+3}=i^3=-i$
$z^{12m-1}+i^{4n+3}=$cis$(pi/6)-i=$cis$(-pi/6)=z$
where cis $=cos +isin$
So, we have $z^{n-94}=1$
$implies12$ divides $n-94$
answered Jan 8 at 5:12
lab bhattacharjeelab bhattacharjee
229k15159279
229k15159279
add a comment |
add a comment |
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$begingroup$
You can use that $e^{2pi i}=1$, from that $z^{95}$ can be expressed as $e^{ix}$ for $x$ in $[0,2pi)$, what is this $x$?
$endgroup$
– lEm
Jan 8 at 5:08
1
$begingroup$
Hello: for future reference, it is always a bad choice to title your question "question on <subject area>". It would be better to copy your actual question into the title, at that rate, since it fits.
$endgroup$
– rschwieb
Jan 8 at 14:48