# Fractional powers of complex numbers

• March 22nd 2009, 10:13 PM
Richmond
Fractional powers of complex numbers
I need help on this one.

Calculate (-2sqrt2i)^(2/3)
• March 22nd 2009, 10:58 PM
Chris L T521
Quote:

Originally Posted by Richmond
I need help on this one.

Calculate (-2sqrt2i)^(2/3)

Note that this is the same as $\left[\left(-2\sqrt{2}i\right)^2\right]^{\frac{1}{3}}=\left(-8\right)^{\frac{1}{3}}$

Now can you find the three roots of unity? First convert this to exponential form and see if you can take it from there. If you still have issues, post back :D
• March 22nd 2009, 11:00 PM
Richmond
thanks i'll give a try.