Mastering the Expansion of Triple Brackets

Nov 24, 2024

Expanding Triple Brackets

Overview

  • Expanding triple brackets involves multiplying three brackets together.
  • The process requires careful attention and clear presentation of workings to avoid mistakes.

Steps for Expanding Triple Brackets

  1. Initial Multiplication:

    • Ignore one bracket and multiply the other two together to form a combined bracket.
    • Essentially, you're performing a double bracket expansion twice.
  2. Final Multiplication:

    • Multiply the resultant bracket from step 1 by the bracket that was initially ignored.
    • This step gives you the final expanded form.

Detailed Process

  • Example 1:

    1. Start with three brackets: For instance, (2x + 3)(x + 2)(x + 4).
    2. Ignore the last bracket initially (x + 4).
    3. Multiply the first two brackets:
      • Multiply terms: 2x by x and 2, 3 by x and 2.
      • Result: 2x^2 + 4x + 3x + 6
      • Simplify to: 2x^2 + 7x + 6
    4. Place the simplified bracket in brackets: (2x^2 + 7x + 6)
    5. Multiply with the ignored bracket (x + 4):
      • Use distributive property:
      • For "x":
        • x * 2x^2 = 2x^3
        • x * 7x = 7x^2
        • x * 6 = 6x
      • For "4":
        • 4 * 2x^2 = 8x^2
        • 4 * 7x = 28x
        • 4 * 6 = 24
    6. Combine like terms:
      • 2x^3 + (7x^2 + 8x^2) + (6x + 28x) + 24
      • Result: 2x^3 + 15x^2 + 34x + 24
  • Example 2:

    1. Choose different brackets: (2x - 1)(x - 2)(x + 3)
    2. Ignore (x + 3) and multiply (2x - 1) with (x - 2):
      • Result: 2x^2 - 4x - x + 2
      • Simplify to: 2x^2 - 5x + 2
    3. Multiply with the ignored bracket (x + 3):
      • For "x": 2x^2 - 5x + 2
        • x * 2x^2 = 2x^3
        • x * -5x = -5x^2
        • x * 2 = 2x
      • For "3":
        • 3 * 2x^2 = 6x^2
        • 3 * -5x = -15x
        • 3 * 2 = 6
    4. Combine like terms:
      • 2x^3 + (6x^2 - 5x^2) + (2x - 15x) + 6
      • Result: 2x^3 + x^2 - 13x + 6

Tips

  • Order of multiplying brackets first does not matter.
  • Use clear arrow diagrams to aid multiplication and avoid confusion.
  • Simplifying at each step helps in managing complexity.

Conclusion

  • Successfully expanding triple brackets requires careful execution of steps.
  • Practice with different bracket combinations to gain proficiency.
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