Find all real and complex roots and type complex answers in the form a+bi.

Question

x^4-9x^2+20=0

Answer 1

x^4-9x^2+20=0

(x^2 - 4)(x^2 - 5) = 0
x^2 = 4 or x^2 = 5
x = ± 2 or x = ± √5

All 4 roots are real, no complex roots