How to Factor Polynomials with 4 Terms – A Simple Step-by-Step Guide

How to Factor Polynomials with 4 Terms A Simple Step-by-Step Guide

To factor polynomials with 4 terms, I first look for any common factors among the terms. If there is a greatest common factor (GCF), I factor it out.

If the polynomial does not immediately suggest a GCF, I consider rearranging the terms to see if they can be grouped in pairs that share a factor. Once the terms are arranged in pairs, I check for common binomial factors between the groups.

Factoring polynomials, especially those with four terms, can often feel like a puzzle where I find the pieces that fit together just right to simplify the expression into a product of factors.

I remember that a polynomial is an expression consisting of variables and coefficients, constructed using only addition, subtraction, multiplication, and non-negative integer exponents.

Being comfortable with these various elements is crucial to successfully factoring the polynomials, effectively reducing the complexity of mathematical problems. It keeps my skills sharp and prepares me for more challenging algebraic tasks.

Steps for Factoring of Polynomials with 4 Terms

When I approach a four-term polynomial, I follow a systematic method to ensure that the factorization is accurate.

Four terms arranged in two pairs. Show grouping of like terms. Use arrows to indicate combining terms. Illustrate factored form

The goal is to express the polynomial as a product of factors, which can be monomials, binomials, trinomials, or other polynomials of lesser degree. Here are the steps I typically use to factorize four-term polynomials:

  1. Identify a Greatest Common Factor (GCF): If there’s a GCF in all four terms, I factor it out. This step simplifies the polynomial, allowing me to see a clearer structure for further factoring.

    • For example: I’d factor $\text{GCF}$ from $6x^3 + 3x^2 – 18x – 9$ as $3(2x^3 + x^2 – 6x – 3)$.
  2. Grouping: Next, I split the terms into two groups and factor out any common binomial factors from each pair. This step is essential in revealing a common factor in the grouped terms.

    • Example Grouping:

      Group 1Group 2
      $x^3 + x^2$$-4x – 4$

      After factoring each group:

      Group 1Group 2
      $x^2(x + 1)$$-4 (x + 1)$
  3. Factor by Grouping: Once the groups are factored, I check if there is a common linear factor between them and factor it out using the distributive property.

    • Example from grouped factors:
    • $(x^2 – 4)(x + 1)$
  4. Special Products: Sometimes, the resulting factors may further simplify using identities like the difference of two squares or the difference of cubes.

    • For example: $(x^2 – 2^2)(x + 1)$ simplifies to $(x + 2)(x – 2)(x + 1)$.
  5. AC Method (if applicable): If the original polynomial is a trinomial, I may use the AC method. With four terms, this would involve combining the middle terms appropriately after finding the product of the “a” and “c” coefficients in a quadratic equation.

By methodically applying these steps when factoring a polynomial with four terms, I ensure that the transformation from the original polynomial to its factored form is complete and accurate. This process allows me to write complex expressions as products of their variable factors and constants.

Factor Polynomials by Grouping

When I approach a four-term polynomial, often referred to as a quadrinomial, I find that the grouping method is a reliable technique. Grouping works by dividing the polynomial into sets, ideally into two groups, and factoring them separately. Here’s how I like to do it:

  1. Dividing into Two Groups: I start by splitting the quadrinomial into two binomial groups. The goal here is to arrange the terms so that each group has a common binomial factor that I can extract.

  2. Factoring Each Group: After grouping, I look for the greatest common factor in each group. If a common binomial factor exists, I factor it out, resulting in an expression of grouped binomials.

Example: Let’s factor the quadrinomial $x^3 – 2x^2 – x + 2$. I would group it as $(x^3 – 2x^2) + (-x + 2)$. Then factor out the greatest common factors from each of these groups to obtain $x^2(x – 2) – 1(x – 2)$.

  1. Extracting the Common Binomial: Now I notice that $(x – 2)$ is a common binomial. So I factor it out, leaving me with $(x – 2)(x^2 – 1)$.

  2. Factor Further if Possible: Sometimes, the groups themselves can be factored further. In our example, $x^2 – 1$ can be factored into $(x + 1)(x – 1)$ since it’s a difference of squares.

So the fully factored form of $x^3 – 2x^2 – x + 2$ is $(x – 2)(x + 1)(x – 1)$.

1Divide the quadrinomial into two groups
2Factor out the greatest common factor from each group
3Extract the common binomial factor
4Factor each group further if possible

There are numerous practice problems available to help you perfect the grouping technique. I always recommend more practice to gain confidence in factoring quadrinomials.

Advanced Factoring Concepts

When I  approach polynomial equations with four terms, I often leverage a range of strategies to simplify the expression into a completely factored form. One of the techniques I find useful is looking at each term’s leading coefficient and constant to identify a potential pattern.

For example, consider a cubic polynomial of the form $ax^3 + bx^2 + cx + d$. I first check if there’s a common factor among all terms. If not, I group them, aiming to factor by grouping. Here’s how I do it step by step:

  1. Group the first two terms and the last two terms: $(ax^3 + bx^2) + (cx + d)$.
  2. Factor out any common factors from each group: $x^2(a x + b) + (c x + d)$.
Original TermsCommon FactorResulting Binomial
$ax^3 + bx^2$$x^2$$ax + b$
$cx + d$None$cx + d$

If the resulting binomial expressions have a common variable or term, I can factor that out, further simplifying the expression.

Another component of advanced factoring involves trial and error to identify binomial factors that multiply together to give the original polynomial.

When considering the solutions, one must remain cognizant of the possible combinations that the terms can create through multiplication.

A completely factored polynomial is as simple as I can make it without altering its value. The essence of factoring, regardless of the terms, is to transform a complex expression into a product of simpler binomials or trinomials.

My goal here is not simply to factor but to unlock the solutions hidden within the algebraic structure.


In learning to factor polynomials, I’ve found that practice truly makes perfect. Starting with simpler cases, like quadratic polynomials, and gradually moving to more complex ones, like those with 4 terms, builds a strong foundation.

Through step-by-step procedures, such as grouping and applying the distributive property, I can transform a cubic polynomial like $x^3 + 3x^2 – x – 3$ into its factored form $(x + 1)(x – 1)(x + 3)$.

I encourage you to keep these strategies in mind: check for a greatest common factor (GCF), group terms to facilitate factoring by grouping, and remember the significance of the zero-product property for finding solutions.

You’ll find that patience and attention to detail are your allies in this process.

Remember, each polynomial function can present its challenges. But with these tools, I feel equipped to tackle them confidently.