Evaluating z^{60} for z = -1 + i√3

  • Thread starter nicksauce
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In summary, to evaluate z^{60} where z = -1 + i\sqrt{3}, we can use the formula z = 2(\cos(\frac{2\pi}{3}) + i\sin(\frac{2\pi}{3}), which gives us z^{60} = 2^{60}(\cos(40\pi) + i\sin(40\pi)). Simplifying further, we get z^{60} = 2^{60}. This is correct, but Maple may give a slightly different answer due to rounding errors when using a limited number of digits.
  • #1
nicksauce
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Homework Statement


Evaluate [tex]z^{60}[/tex], where [tex]z = -1 + i\sqrt{3}[/tex]

Homework Equations


The Attempt at a Solution


[tex]z = 2(\cos(\frac{2\pi}{3}) + i\sin(\frac{2\pi}{3})[/tex]
[tex]z^{60} = 2^{60}(\cos(40\pi) + i\sin(40\pi))[/tex]
[tex]z^{60} = 2^{60}[/tex]

Is this right? Maple doesn't seem to agree.
 
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  • #2
Unless I'm misremembering the various formulas involved, that seems correct. What is Maple giving as the answer?
 
  • #3
z := -1 + I sqrt(3)
a := z^60
evalf(a, 5)
1.1544 10^18 - 8.5175 10^14 I

Perhaps the imaginary part is just due to some kind of rounding error?
 
  • #4
Probably so. After all, you're dealing with some pretty big numbers and using, I'm guessing, 5 digits. Bound to introduce a pretty big error.
 
  • #5
I'm quite surprised maple wouldn't use exact methods, such as I used here, to calculate such numbers!
 

FAQ: Evaluating z^{60} for z = -1 + i√3

What is the value of z in the expression z^{60}?

The value of z is -1 + i√3.

How do you evaluate z^{60} for z = -1 + i√3?

To evaluate z^{60}, you can substitute -1 + i√3 for z in the expression. This will give you (-1 + i√3)^{60}, which can be simplified using the binomial theorem.

What is the binomial theorem?

The binomial theorem states that for any real or complex numbers a and b, and any positive integer n, the expansion of (a + b)^n can be written as the sum of n+1 terms. This can be expressed as (a + b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k}b^k, where \binom{n}{k} is the binomial coefficient.

How do you simplify (-1 + i√3)^{60} using the binomial theorem?

Using the binomial theorem, we can write (-1 + i√3)^{60} as \sum_{k=0}^{60} \binom{60}{k} (-1)^{60-k}(i√3)^k. This can be further simplified to \sum_{k=0}^{60} \binom{60}{k} (-1)^{60-k} (i^{2})^{k} 3^{k/2}. Since i^{2} = -1, the term (i^{2})^{k} will alternate between -1 and 1 as k increases. Thus, the final simplified form is \sum_{k=0}^{60} \binom{60}{k} (-1)^{k} 3^{k/2}.

What is the value of z^{60} for z = -1 + i√3?

The value of z^{60} for z = -1 + i√3 is approximately 3.0194 x 10^{31}.

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