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student1988

  • 3 years ago

Write the expression in the standard form a + bi. (View my question to see it written, sorry for the inconvenience)

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  1. student1988
    • 3 years ago
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    |dw:1352848428519:dw|

  2. student1988
    • 3 years ago
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    That's raised to the fourth power.. I got -4. Can someone tell me if i am correct? :)

  3. asnaseer
    • 3 years ago
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    how did you arrive at your answer?

  4. student1988
    • 3 years ago
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    Is it wrong? i used De Moivre's Theorem

  5. asnaseer
    • 3 years ago
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    so did you first convert it to the form \(e^{i\theta}\)?

  6. student1988
    • 3 years ago
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    but i wasn't sure if it was right because the complex number i disappeared!

  7. student1988
    • 3 years ago
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    Not sure what you mean by that

  8. asnaseer
    • 3 years ago
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    your answer is correct - I am just making sure you used this way of getting to the answer rather than trying to expand the braces with the fourth power :)

  9. student1988
    • 3 years ago
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    |dw:1352848854469:dw|

  10. student1988
    • 3 years ago
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    i used this form

  11. asnaseer
    • 3 years ago
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    the method I used was to first convert it as follows:\[(\sqrt{2}(\cos(3\pi/4)+i\sin(3\pi/4))^4=(\sqrt{2}e^{i3\pi/4})^4\]

  12. student1988
    • 3 years ago
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    oh, i haven't seen this form. Could you tell me where I can read on this form?

  13. asnaseer
    • 3 years ago
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    it uses the identity:\[e^{i\theta}=\cos(\theta)+i\sin(\theta)\]

  14. asnaseer
    • 3 years ago
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    See here: http://en.wikipedia.org/wiki/Euler%27s_identity

  15. student1988
    • 3 years ago
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    Euler's Formula. Thanks, i'll read it! Thank you! :)

  16. asnaseer
    • 3 years ago
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    Sorry - wrong link, I meant this one: http://en.wikipedia.org/wiki/Euler%27s_formula

  17. asnaseer
    • 3 years ago
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    yup - you got it!

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