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Factoring Trinomials with Leading Coefficient

May 15, 2025

Factoring Trinomials with Leading Coefficient Not Equal to One

Introduction

  • Discusses a method for factoring trinomials where the leading coefficient is not one.
  • Useful technique for those looking to improve their skills in factoring, particularly relevant in the U.S.

Method Explanation

Example 1

  1. Initial Step

    • Take the leading coefficient (12) and multiply it by the constant term (6).
    • Expression changes from 12x^2 + 17x + 6 to x^2 + 17x + 72.
  2. Factoring Process

    • Set up the factor format: (X + _)(X + _).
    • Find two numbers that multiply to 72 and add up to 17.
    • List of factor pairs for 72:
      • 1 and 72
      • 2 and 36
      • 3 and 24
      • 4 and 18
      • 6 and 12
      • 8 and 9
    • Numbers that add up to 17: 8 and 9.
    • Insert into the factor format: (X + 8)(X + 9).
  3. Reverse Multiplication Adjustment

    • Divide the factors 8 and 9 by the original leading coefficient (12):
      • Reduce fractions: (X + 2/3)(X + 3/4).
    • Adjust by multiplying the denominator with X:
      • (3X + 2)(4X + 3).
  4. Verification

    • Expanding gives 12x^2 + 17x + 6, matching the original expression.

Example 2

  1. Initial Step

    • Multiply leading coefficient of 6 by constant term, resulting in x^2 - 5X - 24.
  2. Factoring Process

    • Set up the factor format: (X + _)(X - _) because of the negative third term.
    • Find two numbers that multiply to 24 and subtract to get 5.
    • List of factor pairs for 24:
      • 1 and 24
      • 2 and 12
      • 3 and 8
      • 4 and 6
    • Numbers that subtract to 5: 8 and 3.
    • Insert into the factor format: (X - 8)(X + 3).
    • Place larger number (8) with the negative sign due to -5 coefficient.
  3. Reverse Multiplication Adjustment

    • Divide the factors 3 and 8 by the original leading coefficient (6):
      • Reduce fractions: (X + 1/2)(X - 4/3).
    • Adjust by multiplying the denominator with X:
      • (2X + 1)(3X - 4).
  4. Verification

    • Expanding gives 6x^2 - 5x - 4, confirming the factorization.

Conclusion

  • The method provides a systematic approach to factoring non-standard trinomials.
  • Encouragement to practice and apply this method for efficiency in solving such problems.

Additional Notes

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