
Douglas B. answered 01/26/22
Linear algebra tutor with masters degree in applied math
Let's work through the first one. Replace i with e^(i*pi/2).
i^(1/4) = [e^(i*pi/2)]^(1/4) = e^(i*pi/8) = cos(pi/8) + i*sin(pi/8).
It turns out that you can find the exact values (in terms of roots) of cos(pi/8) and sin (pi/8).
That is a challenge for you.