HELP PLS

If a number is written in  r·cis( theta )  form, then its four fourth roots are:

     r^1/4·cis( theta/4 ),     r^1/4·cis( theta/4 + pi/4 ),     r^1/4·cis( theta/4 + 2pi/4 ),     r^1/4·cis( theta/4 + 3pi/4 ).

 

Writing  -4  into  r·cis( theta )  form:  -4  =  4·cis( pi )

 

So its four fourth roots are: 

      4^1/4·cis( pi/4 ),     4^1/4·cis( pi/4 + pi/4 ),     4^1/4·cis( pi/4 + 2pi/4 ),     4^1/4·cis( pi/4 + 3pi/4 ).

 

[You should simplify these answers.]