Did I do these right??

Problem #1:  you handled the constants correctly; however, the angles should be subtracted, not divided.

Problem #2:  r  =  sqrt( (-2)² + (-2)² )  =  sqrt( 4 + 4 )  =  sqrt(8)

angle  =  tan^-1( -2 / -2 )  =  tan^-1( 1 )      =  5pi/4

To find the primary cube root, find the cube root of the r value and divide the angle by 3.

To find the next cube root, the r value remains the same but you need to add 2pi/3 to the angle.

To find the last cube root, the r value remains the same but you need to add another 2pi/3 to the angle.