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compute the following: 1. 3^i 2. e^2log(-1)?

is the answer to 2, just going to be -1 squared, I mean 1?

Update:

do I have to use any laws of complex variables to solve them?

3 Answers

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  • 1 decade ago
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    1. For complex numbers we use that

    a^z = e^log(a^z) = e^(z*loga).

    Then 3^i = e^(i log3) and you need to find the value of the complex logarithm

    log z = log|z| + i Argz + 2k*pi*i, where k any integer

    log 3 = log|3| + i Arg3 + 2k*pi*i = log3 + i*0 + 2k*pi*i = log3 +2k*pi*i.

    Then

    3^i = e^[ i*(log3 + 2k*pi*i)] = e^( i*log3 - 2k*pi) =[e^(i*log3)] * [e^(-2k*pi)]

    According to Euler's formula e^(i*y) = cosy + i*siny, so

    3^i = [cos(log3) + i*sin(log3)] *[e^(-2k*pi)] or

    3^i = [e^(-2k*pi)] cos(log3) + i* [e^(-2k*pi)] sin(log3), k any integer. <== ANS

    In case you use just principal value of the logarithm we get

    3^i = e^(i*Log3) = e^[ i* (log|3| + i Arg3)] =

    = cos(log3) + i* sin(log3) ≈ 0.455 + 0.891 i <=== principal value

    2. e^2log(-1) = e^2*(log|-1| + i*Arg(-1) + 2k*pi*i) =

    = e^2(log1 + i*pi + 2k*pi*i) = e^2(2k + 1)*i*pi = e^(4k + 2) * i*pi = 1.

  • 1 decade ago

    1) 3^i = .4548324228 + 08905770417i

    2) e^2log(-1) = -.915985097 + .4012122906i

  • 1 decade ago

    1. 3^i not sure about

    2. domain error on calculator... says... no. if it was equal to 1... then the calculator should yield an answer of 1... it doesn't.

    also order of operations says... do the argument first.

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