Q.If one root of the quadratic equation \(3x^2 + (k - 1)x + 9 = 0\) is 3, then what will be the value of \(k\)? (a) -11 (b) 11 (c) 12 (d) 14
Answer: A
Given: \(3x^2 + (k - 1)x + 9 = 0\) If one root is 3, then: Substitute \(x = 3\): ⇒ \(3 \times 3^2 + (k - 1) \times 3 + 9 = 0\) ⇒ \(27 + 3k - 3 + 9 = 0\) ⇒ \(3k + 33 = 0\) ⇒ \(3k = -33\) ⇒ \(k = -11\)
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