What is the value of k if the roots of the equation x^2 - kx + 9 = 0 are real an

Practice Questions

Q1
What is the value of k if the roots of the equation x^2 - kx + 9 = 0 are real and distinct?
  1. k > 18
  2. k < 18
  3. k = 18
  4. k = 9

Questions & Step-by-Step Solutions

What is the value of k if the roots of the equation x^2 - kx + 9 = 0 are real and distinct?
  • Step 1: Identify the equation given, which is x^2 - kx + 9 = 0.
  • Step 2: Recognize that for the roots of a quadratic equation to be real and distinct, the discriminant must be greater than zero.
  • Step 3: The discriminant (D) for the equation ax^2 + bx + c = 0 is given by the formula D = b^2 - 4ac.
  • Step 4: In our equation, a = 1, b = -k, and c = 9.
  • Step 5: Substitute the values into the discriminant formula: D = (-k)^2 - 4(1)(9).
  • Step 6: Simplify the expression: D = k^2 - 36.
  • Step 7: Set the discriminant greater than zero for real and distinct roots: k^2 - 36 > 0.
  • Step 8: Rearrange the inequality: k^2 > 36.
  • Step 9: Solve for k by taking the square root: k < -6 or k > 6.
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