If 3 is a solution to the equation 3x² + (k − 1)x + 9 = 0, what is the value of k?
Q1. If 3 is a solution to the equation 3x² + (k − 1)x + 9 = 0, what is the value of k?
Answer: -11
Explanation: Substituting x=3: 3(9)+(k−1)(3)+9 = 0 → 27+3k−3+9 = 0 → k = −11.