What is the value of k for which the equation x^2 + kx + 16 = 0 has no real root

Practice Questions

Q1
What is the value of k for which the equation x^2 + kx + 16 = 0 has no real roots? (2021)
  1. -8
  2. -4
  3. 4
  4. 8

Questions & Step-by-Step Solutions

What is the value of k for which the equation x^2 + kx + 16 = 0 has no real roots? (2021)
  • Step 1: Identify the equation given, which is x^2 + kx + 16 = 0.
  • Step 2: Understand that for a quadratic equation to have no real roots, the discriminant must be less than zero.
  • Step 3: The discriminant formula for the equation ax^2 + bx + c is given by D = b^2 - 4ac.
  • Step 4: In our equation, a = 1, b = k, and c = 16.
  • Step 5: Substitute the values into the discriminant formula: D = k^2 - 4*1*16.
  • Step 6: Simplify the expression: D = k^2 - 64.
  • Step 7: Set the discriminant less than zero for no real roots: k^2 - 64 < 0.
  • Step 8: Rearrange the inequality: k^2 < 64.
  • Step 9: Take the square root of both sides: -8 < k < 8.
  • Step 10: Conclude that the values of k for which the equation has no real roots are k < 8 and k > -8.
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