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

x^2+20=0

x = or x =

If g(x) = x+1/ x-2 and h (x) =4 - x , what is the value of ( g*h) (-3)?

Find the zeros of each function. f(x) = x^2 + 5x - 6

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )