Find the value of Z^69

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May 3rd 2009, 09:45 PM
zorro

Find the value of Z^69

If $z = \frac{\sqrt{3}+1}{2}$ find the value of $z^{69}$
May 4th 2009, 12:03 PM
vemrygh

Write the complex number on the form $z=re^{\theta i}$ , and then compute $z^{69}=r^{69}e^{69\theta i}.$
May 4th 2009, 01:30 PM
Soroban

Hello, zorro!

Quote:

$\text{If }z = \frac{\sqrt{3}+1}{2}, \text{ find the value of }z^{69}$

Convert $z$ to polar form: . $z \:=\:\cos\tfrac{\pi}{6} + i\sin\tfrac{\pi}{6}$

Then use DeMoivre's Theorem: . $(\cos\theta + i\sin\theta)^n \;=\;\cos(n\theta) + i\sin(n\theta)$
May 5th 2009, 12:49 AM
Calculus26

Am I missing something here?

I would agree with y'all if it were

[3^(1/2)+i]/2

But as z is not complex??????
May 5th 2009, 05:16 AM
mr fantastic

Quote:

Originally Posted by Calculus26

Am I missing something here?

I would agree with y'all if it were

[3^(1/2)+i]/2

But as z is not complex??????

Probably a typo. Clarification might be given in a few weeks.
June 28th 2009, 02:18 AM
zorro

Answer please

i have tried to solve the problem but dont know what is the right answer .Could u please let me know what is the right answer .........
June 28th 2009, 03:07 AM
Plato

Quote:

Originally Posted by zorro

i have tried to solve the problem but dont know what is the right answer .Could u please let me know what is the right answer .........

Is the number z complex or real?

Is it $\frac{\sqrt{3}+{\color{red}i}}{2}$ or just $\frac{\sqrt{3}+1}{2}$ ?
June 28th 2009, 03:29 AM
aidan

Quote:

Originally Posted by zorro

If $z = \frac{\sqrt{3}+1}{2}$ find the value of $z^{69}$

$z = \frac{\sqrt{3}+1}{2}$ = 1.366025404 approx.

find the value of $z^{69}$
${1.366025404}^{69} = 2221547172.+decimaldigits$
How many decimals places are needed.

or do you need the binominal expansion of this
$\frac{ \left ( \sqrt{3}+1 \right )^{69} } {2^{69}}$
June 29th 2009, 11:47 PM
zorro

Want to know the right solution

If $z=\frac{\sqrt{3}+1}{2}$ , find the value of $z^{69}$
June 30th 2009, 12:37 AM
Moo

Okay, let me explain it to you :

In the form you've written, it is not possible to get a nice form for the exact value !
If it were $\frac{\sqrt{3}+i}{2}$ , then the problem would be less meaningless.

Consider again your problem.
June 30th 2009, 12:53 AM
mr fantastic

Quote:

Originally Posted by zorro

If $z=\frac{\sqrt{3}+1}{2}$ , find the value of $z^{69}$

There is no simple exact answer to the question you have posted. This has been said several times now.

So either the question has a mistake in it or an approximate answer is required. If the former, then the likely question and its answer has been given in this thread. If the latter, the answer has also been given.

I don't see how any further progress can be made here unless the OP is prepared to acknowledge and address the above issues.
July 4th 2009, 01:46 PM
aidan

The EXACT answer:

$\frac {479994729504490251817683255296 \times \sqrt{3+1}}{ 590295810358705651712}$
July 4th 2009, 02:02 PM
Plato

1 Attachment(s)

Quote:

Originally Posted by aidan

The EXACT answer:
$\frac {479994729504490251817683255296 \times \sqrt{3+1}}{ 590295810358705651712}$

As you can see your exact solution is a bit off.

Go to Wolfram|Alpha. Type “((sqrt[3]+1)/2)^69” exactly then click the “=” at the right-hand side of the input box.
July 4th 2009, 08:53 PM
CaptainBlack

Quote:

Originally Posted by aidan

The EXACT answer:

$\frac {479994729504490251817683255296 \times \sqrt{3+1}}{ 590295810358705651712}$

Quote:

Originally Posted by Plato

As you can see your exact solution is a bit off.

Go to Wolfram|Alpha. Type “((sqrt[3]+1)/2)^69” exactly then click the “=” at the right-hand side of the input box.

What is more interesting about aidan's answer (other than the obvious typo: $\sqrt{3+1}$ ) is why is it wrong (at least I think this is of interest).

Cb
July 4th 2009, 11:54 PM
zorro

Sorry for the typo mistake

Quote:

Originally Posted by Plato

Is the number z complex or real?

Is it $\frac{\sqrt{3}+{\color{red}i}}{2}$ or just $\frac{\sqrt{3}+1}{2}$ ?

It is
$\frac{\sqrt{3}+i}{2}$
Now please can any one give me the right solution to this question?

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