One or more options correct
Let be the roots of . Which of the following is/are correct?
- A.
- B.
- C. The equation has exactly one real root
- D. The cubic having roots is
Show answer and solution
Answer: A, C, D
From Vieta, , , . Then , so (A) is true, and the negative value just reflects the complex roots. By Newton's identity, , so (B) with is false. The discriminant of the cubic is , so there is one real root and a complex pair; (C) is true. The new cubic has coefficients: sum of roots giving coefficient ; sum of products ; product giving constant . Hence , and (D) is true.
Saved on this device. Sign in or create a free account to keep it on every device.