Are you saying that z = -21-20i ?
If so, then w = (-21-20i)^(1/2)
= 29 arctan(-20/-21)
= 29 cis -136.4°
So, w = √29 cis -68.2° = 2 - 5i
check: (2-5i)^2 = 4-25 - 20i = -21-20i
Find w=a + bi = √z , where a and b are real numbers.
√-21-20i
1 answer