If the roots of the equation x^2 + 4x + k = 0 are real and equal, what is the mi

Practice Questions

Q1
If the roots of the equation x^2 + 4x + k = 0 are real and equal, what is the minimum value of k?
  1. 0
  2. -4
  3. -8
  4. -16

Questions & Step-by-Step Solutions

If the roots of the equation x^2 + 4x + k = 0 are real and equal, what is the minimum value of k?
  • Step 1: Identify the equation given, which is x^2 + 4x + k = 0.
  • Step 2: Recall that for a quadratic equation ax^2 + bx + c = 0, the discriminant (D) is given by the formula D = b^2 - 4ac.
  • Step 3: In our equation, a = 1, b = 4, and c = k.
  • Step 4: Substitute the values of a, b, and c into the discriminant formula: D = 4^2 - 4(1)(k).
  • Step 5: Simplify the expression: D = 16 - 4k.
  • Step 6: For the roots to be real and equal, the discriminant must be equal to zero: 16 - 4k = 0.
  • Step 7: Solve the equation 16 - 4k = 0 for k.
  • Step 8: Rearrange the equation: 4k = 16.
  • Step 9: Divide both sides by 4: k = 4.
  • Step 10: Conclude that the minimum value of k for the roots to be real and equal is 4.
  • Discriminant of a Quadratic Equation – The discriminant (D) of a quadratic equation ax^2 + bx + c = 0 is given by D = b^2 - 4ac. For the roots to be real and equal, D must be equal to zero.
  • Quadratic Equations – Understanding the standard form of quadratic equations and how to manipulate them to find roots.
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