If the quadratic equation x^2 + 2x + k = 0 has roots 1 and -3, what is the value

Practice Questions

Q1
If the quadratic equation x^2 + 2x + k = 0 has roots 1 and -3, what is the value of k? (2022)
  1. -3
  2. 2
  3. 3
  4. 4

Questions & Step-by-Step Solutions

If the quadratic equation x^2 + 2x + k = 0 has roots 1 and -3, what is the value of k? (2022)
  • Step 1: Identify the given quadratic equation, which is x^2 + 2x + k = 0.
  • Step 2: Recognize that the roots of the equation are given as 1 and -3.
  • Step 3: Use the property of the product of the roots of a quadratic equation, which states that for an equation in the form ax^2 + bx + c = 0, the product of the roots (r1 * r2) is equal to c/a.
  • Step 4: In our equation, a = 1 and c = k. Therefore, the product of the roots (1 * -3) should equal k.
  • Step 5: Calculate the product of the roots: 1 * -3 = -3.
  • Step 6: Set the product equal to k: k = -3.
  • Step 7: Conclude that the value of k is -3.
  • Quadratic Equations – Understanding the relationship between the coefficients of a quadratic equation and its roots, specifically using Vieta's formulas.
  • Roots of Quadratic Equations – Identifying and applying the properties of roots, including their sum and product.
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