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Factoring Trinomials and Polynomials: College Algebra Study Notes

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Polynomials and Factoring

Introduction to Polynomials

Polynomials are algebraic expressions consisting of variables and coefficients, combined using addition, subtraction, and multiplication. Understanding how to simplify and factor polynomials is a foundational skill in college algebra.

  • Polynomial: An expression of the form where are constants.

  • Degree: The highest power of the variable in the polynomial.

  • Monomial, Binomial, Trinomial: Polynomials with one, two, or three terms, respectively.

Simplifying Polynomials

Simplifying polynomials involves combining like terms and performing basic arithmetic operations.

  • Example:

    • Expand using distributive property (FOIL):

  • Example:

    • Expand:

  • Example:

    • Expand:

Factoring Trinomials

Factoring Trinomials of the Form

Factoring trinomials is the process of expressing a quadratic polynomial as a product of two binomials. This is a key skill for solving quadratic equations and simplifying expressions.

  • To factor , find two integers that multiply to c and add to b.

  • Write the trinomial as , where and are the integers found.

Example: Factor

  • Find two numbers that multiply to 12 and add to 7: 3 and 4.

  • So,

Factoring Practice Sets

  • Set 1 (All positive coefficients):

  • Set 2 (Mixed signs):

  • Set 3 (Negative coefficients):

  • Set 4 (Positive constant term):

Mixed Practice

Factoring with a Greatest Common Factor (GCF)

Factoring Out the GCF

Before factoring a trinomial, always check for a Greatest Common Factor (GCF) among all terms. Factoring out the GCF simplifies the polynomial and makes further factoring easier.

  • GCF: The largest integer or variable expression that divides each term of the polynomial.

  • Example:

    • GCF is 4:

    • Factor the trinomial:

  • Example:

    • GCF is 2:

    • Factor the trinomial:

Factoring Higher Degree Polynomials

Some polynomials may have degrees higher than 2 or include multiple variables. The process is similar: factor out the GCF, then factor the remaining polynomial if possible.

  • Example:

    • GCF is 3a:

    • Factor the trinomial:

  • Example:

    • GCF is 5y:

    • Factor the trinomial:

Checking Factoring by FOIL

FOIL Method

The FOIL method (First, Outer, Inner, Last) is used to multiply two binomials and check the correctness of factoring.

  • Example:

    • First:

    • Outer:

    • Inner:

    • Last:

    • Sum:

Summary Table: Factoring Trinomials

Trinomial

Factored Form

GCF (if any)

None

4

None

Visual Example: Factoring Trinomials

Trinomials like can be factored back into a product of binomials. This process is essential for solving quadratic equations and simplifying algebraic expressions.

Factoring trinomials visual exampleAdditional info: The notes above expand on the brief worksheet instructions, providing definitions, step-by-step examples, and a summary table for reference. This guide is suitable for college algebra students preparing for exams on polynomial factoring.

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