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

Practice Questions

Q1
What is the value of k if the roots of the equation x^2 + kx + 9 = 0 are imaginary?
  1. k < 0
  2. k > 0
  3. k = 0
  4. k ≤ 0

Questions & Step-by-Step Solutions

What is the value of k if the roots of the equation x^2 + kx + 9 = 0 are imaginary?
  • Step 1: Identify the equation given, which is x^2 + kx + 9 = 0.
  • Step 2: Understand that the roots of a quadratic equation are imaginary when the discriminant is less than zero.
  • Step 3: The discriminant (D) for the equation ax^2 + bx + c = 0 is calculated using the formula D = b^2 - 4ac.
  • Step 4: In our equation, a = 1, b = k, and c = 9. So, the discriminant becomes D = k^2 - 4*1*9.
  • Step 5: Simplify the discriminant: D = k^2 - 36.
  • Step 6: Set the discriminant less than zero for the roots to be imaginary: k^2 - 36 < 0.
  • Step 7: Rearrange the inequality: k^2 < 36.
  • Step 8: Take the square root of both sides: -6 < k < 6.
  • Step 9: This means k can be any value between -6 and 6, but not including -6 and 6.
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