Answer:
[tex] y = 4 + 3 \sqrt{7} i[/tex]
Step-by-step explanation:
[tex](y-4)^2+63=0 \\ \\ (y-4)^2 = - 63 \\ \\ (y-4)= \sqrt{ - 63} \\ \\ y - 4 = 3 \sqrt{7} i \\ \\ y = 4 + 3 \sqrt{7} i[/tex]