Stuck on a couple math questions! Could anyone help me understand them?

1. What is the solution of the equation when solved over the complex numbers?

x^2+24=0



Enter your answers, as exact values, in the boxes.

x = __or x =__

9. Solve.

x^2−9x+3=0



Enter your answers, as exact values, in the boxes.

x =___ or x =____

11. Solve for x over the complex numbers.

x^2+4x+13=0



Enter your answers in the boxes.

x =___ or x =___