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Complex number root

  • 04-08-2010 1:35pm
    #1
    charlie_says
    Registered Users, Registered Users 2 Posts: 1,666 ✭✭✭


    Trying to figure out where I have gone wrong here:

    Question is express in terms of x + iy

    (1-i)^5

    I got r=2^1/2

    and theta = pi/4

    but when I work through

    (z)^5=(re^i(pi/4))^5

    then I get my answer as 5pi/4 and (5pi/4)i when it should be -4 and +4i

    Any tips?


Comments

  • #2
    CJC86
    Registered Users, Registered Users 2 Posts: 360 ✭✭CJC86


    Check your work, your theta value is actually wrong at the moment.

    If z = r*e^i(theta), then z^5 = r^5*e^5i(theta). You have only multiplied your theta value by 5, rather than multiplying it by 5 and then plugging it back in to the exponential function. You also forgot to raise the power of r (in fact, you forgot about r completely).


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