If a quadratic equation has an imaginary root -4i, then its conjugate i. E. 4i will be the other root of the equation. Step-by-step explanation: a. The only imaginary root of a quadratic equation is -4i, this is not possible. Because, if a quadratic equation has an imaginary root -4i, then it's conjugate i. E. 4i will be the other root of the equation. b. So, the two roots of a quadratic equation are imaginary and they are 4i and -4i. Therefore, the equation will be (x - 4i)(x + 4i) = 0 ⇒ ⇒ ⇒ (Answer)