Skyrocket Quadratic Trinomial Skills: Killer Easy Tips 10

Factorising Non-Monic Quadratic Trinomials Common Factors

Factorising Non-Monic Quadratic Trinomials: Common Factors

As a student, mastering the art of factorising non-monic quadratic trinomials with common factors is a crucial skill for your success in mathematics. Non-monic quadratic trinomials with common factors are expressions in the form $ax^2 + bx + c$, where $a$, $b$, and $c$ are constants, $a \neq 0$, and the terms of the trinomial share a common factor. With these killer easy tips, you’ll be able to skyrocket your quadratic trinomial factoring skills in no time!

Understand the Goal of Factorising

Before diving into the tips and techniques, it’s essential to understand the goal of factorising quadratic trinomials with common factors. Factorising means rewriting the quadratic trinomial as a product of a common factor and a factored trinomial. In other words, we want to find a common factor $d$ and numbers $p$ and $q$ such that:

$ax^2 + bx + c = d(px^2 + qx + r)$

Where $d$ is the greatest common factor (GCF) of $a$, $b$, and $c$, and $px^2 + qx + r$ is a factored trinomial.

Understanding this goal will help you approach factorising with clarity and purpose.

Killer Tip #1: Identify the Coefficients and Constant Term

To begin factorising a non-monic quadratic trinomial with common factors, identify the coefficients $a$, $b$, and the constant term $c$. These values will be your guiding light throughout the factoring process. Let’s consider an example:

$6x^2 + 15x + 9$

In this case, $a = 6$, $b = 15$, and $c = 9$.


$6x^2 + 15x + 9$ $a = 6$, $b = 15$, $c = 9$

Killer Tip #2: Find the Greatest Common Factor (GCF)

To factor a non-monic quadratic trinomial with common factors, find the greatest common factor (GCF) of the coefficients $a$, $b$, and the constant term $c$. The GCF is the largest positive integer that divides each of the terms without leaving a remainder.

In our example, the GCF of $6$, $15$, and $9$ is $3$.

$GCF(6, 15, 9) = 3$

This GCF will be the common factor you’ll factor out of the trinomial.


$6x^2 + 15x + 9$ $GCF(6, 15, 9) = 3$

Killer Tip #3: Factor Out the GCF

Once you have found the GCF, factor it out of each term of the trinomial. This step will leave you with a new trinomial that is easier to factor further. In our example, we factor out the GCF of $3$:

$6x^2 + 15x + 9 = 3(2x^2 + 5x + 3)$

The resulting trinomial, $2x^2 + 5x + 3$, will be the focus of the next steps.


$6x^2 + 15x + 9 = 3(2x^2 + 5x + 3)$

Killer Tip #4: Factor the Resulting Trinomial

Now that you have factored out the GCF, you can proceed to factor the resulting trinomial using any of the appropriate methods, such as the trial and error method, the AC method, or the decomposition method.

In our example, let’s use the trial and error method. We need to find two numbers whose product is $2 \times 3 = 6$ and whose sum is $5$. The numbers $2$ and $3$ satisfy these conditions:

$2x^2 + 5x + 3 = (2x + 3)(x + 1)$


$2x^2 + 5x + 3 = (2x + 3)(x + 1)$

Killer Tip #5: Write the Final Factored Form

To write the final factored form, combine the GCF and the factored trinomial you obtained in the previous steps. The final factored form will be a product of the GCF and the factored trinomial.

In our example, the final factored form is:

$6x^2 + 15x + 9 = 3(2x + 3)(x + 1)$


$6x^2 + 15x + 9 = 3(2x + 3)(x + 1)$

Practice Makes Perfect

To reinforce your understanding and build your factoring skills, practice factorising non-monic quadratic trinomials with common factors regularly. Start with simple examples and gradually progress to more challenging ones. Remember, the more you practice, the more confident and proficient you’ll become in factoring quadratic trinomials.

Examples to Practice:

  1. $8x^2 + 12x + 4$
  2. $15x^2 – 25x + 10$
  3. $18x^2 + 27x – 9$
  4. $20x^2 – 30x + 10$
  5. $24x^2 – 14x – 6$

Troubleshooting Common Mistakes

As you practice factorising non-monic quadratic trinomials with common factors, be aware of common mistakes students often make:

  1. Forgetting to find the GCF: Always start by finding the greatest common factor of the coefficients and constant term before attempting to factor the trinomial.
  2. Incorrectly calculating the GCF: Double-check your calculations when finding the GCF to ensure you have the correct common factor.
  3. Overlooking the signs when factoring: Pay attention to the signs of the terms in the trinomial and the resulting factored form to avoid errors.
  4. Mixing up the order of the factors: The order of the factors in the final factored form does not matter, as multiplication is commutative. However, be consistent in your approach to avoid confusion.

By being mindful of these common mistakes, you can avoid pitfalls and strengthen your factoring skills.


Factorising non-monic quadratic trinomials with common factors may seem daunting at first, but with these killer easy tips, you’ll be able to master this essential skill in no time. Remember to identify the coefficients and constant term, find the greatest common factor (GCF), factor out the GCF, factor the resulting trinomial, and write the final factored form. Practice regularly, start with simple examples, and gradually challenge yourself with more complex trinomials.

As you gain confidence in factoring non-monic quadratic trinomials with common factors, you’ll be well-prepared to tackle more advanced topics in algebra and beyond. Keep honing your skills, and don’t hesitate to seek help from your teachers or tutors if you encounter difficulties along the way. With dedication and practice, you’ll become a quadratic trinomial factoring pro in no time!

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