Complex Number

 
Sumber :  http://tutorial.math.lamar.edu/Extras/ComplexPrimer/Roots.aspx


Compute .

Solution

Of course we could just do this by multiplying the number out, but this would be time consuming and prone to mistakes.  Instead we can convert to exponential form and then use (1) to quickly get the answer.

Here is the exponential form of .

                     

                                                           

Note that we used the principal value of the argument for the exponential form, although we didn’t have to.

Now, use (1) to quickly do the computation.