If the roots of the equation x² + 7x + p = 0 are -3 and -4, find p. (2019)

Practice Questions

Q1
If the roots of the equation x² + 7x + p = 0 are -3 and -4, find p. (2019)
  1. 12
  2. 7
  3. 15
  4. 10

Questions & Step-by-Step Solutions

If the roots of the equation x² + 7x + p = 0 are -3 and -4, find p. (2019)
  • Step 1: Identify the given quadratic equation, which is x² + 7x + p = 0.
  • Step 2: Note the roots of the equation, which are -3 and -4.
  • Step 3: Calculate the sum of the roots: -3 + -4 = -7.
  • Step 4: The sum of the roots can also be expressed as -b/a, where b is the coefficient of x. Here, b = 7 and a = 1, so -b/a = -7.
  • Step 5: Since the sum of the roots matches, we can proceed to find the product of the roots.
  • Step 6: Calculate the product of the roots: -3 * -4 = 12.
  • Step 7: The product of the roots can also be expressed as c/a, where c is the constant term (p in this case) and a is the coefficient of x². Here, c = p and a = 1, so c/a = p.
  • Step 8: Since the product of the roots is 12, we have p = 12.
  • Quadratic Equations – Understanding the relationship between the coefficients of a quadratic equation and its roots through Vieta's formulas.
  • Sum and Product of Roots – Applying the properties of the sum and product of the roots of a quadratic equation to find unknown coefficients.
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