2021 · Q71
For what values of k, the roots of 9x² + 8kx + 16 = 0 are real and equal?
Elementary MathematicsAlgebra
- A0
- B−2, 2
- C−3, 3
- D−4, 4
Explanation
Equal real roots need the discriminant to be zero: (8k)² − 4·9·16 = 64k² − 576 = 0. So k² = 9 and k = ±3. Hence option C.