If the roots of the equation x^2 + 5x + k = 0 are real and distinct, what is the

Practice Questions

Q1
If the roots of the equation x^2 + 5x + k = 0 are real and distinct, what is the condition on k? (2023)
  1. k < 25
  2. k > 25
  3. k = 25
  4. k ≤ 25

Questions & Step-by-Step Solutions

If the roots of the equation x^2 + 5x + k = 0 are real and distinct, what is the condition on k? (2023)
  • Step 1: Identify the equation given, which is x^2 + 5x + k = 0.
  • Step 2: Understand 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 calculated using the formula D = b^2 - 4ac.
  • Step 4: In our equation, a = 1, b = 5, and c = k. So, we substitute these values into the discriminant formula: D = 5^2 - 4(1)(k).
  • Step 5: Calculate 5^2, which is 25. Now we have D = 25 - 4k.
  • Step 6: Set up the inequality for the discriminant to be greater than zero: 25 - 4k > 0.
  • Step 7: Solve the inequality: First, subtract 25 from both sides: -4k > -25.
  • Step 8: Divide both sides by -4. Remember, when dividing by a negative number, the inequality sign flips: k < 25.
  • Step 9: Conclude that for the roots to be real and distinct, the condition on k is k < 25.
  • Discriminant of a Quadratic Equation – The discriminant (D) of a quadratic equation ax^2 + bx + c = 0 is given by D = b^2 - 4ac. It determines the nature of the roots: if D > 0, the roots are real and distinct; if D = 0, the roots are real and equal; if D < 0, the roots are complex.
  • Conditions for Real and Distinct Roots – For the roots of a quadratic equation to be real and distinct, the discriminant must be positive.
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