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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?
do I have to use any laws of complex variables to solve them?
3 Answers
- Tabula RasaLv 61 decade agoFavorite Answer
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.
- ra†iaLv 71 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.