Question

If one root of a cubic equation is real and second root is imaginary, then what can be said about the third root?

• A. Can be imaginary or real
• B. Must be real
• C. Must be Imaginary
• D. must be zero

Answer 1

The correct option is C Must be Imaginary

Cubic Equations can have at max $3$ roots. Also, imaginary roots always occur in a pair of conjugates.
Since here one root is real and the other is imaginary, the third one must be imaginary and it will be the conjugate of the second root.