Factoring
April 16, 2025

Introduction
Factoring is the process of breaking down a number or an algebraic expression into simpler parts (called factors) that, when multiplied together, give back the original expression. Here are some of the factoring techniques that will be discussed in this lesson.
Greatest Common Monomial Factor (GCMF)
Factor out the greatest common factor from all terms.
Factor \bf{25x^2 + 30x}
We begin by finding the greatest common factor (GCF):
Rewrite each term using the GCF (5) (x) = 5x:
Factor out 5x:
Factor \bf{6x^4 - 15x^3 + 3x^2}
We begin by finding the greatest common factor (GCF):
Rewrite each term using GCF (3)(x)(x) = 3x^2:
Factor out 3x2 :
Factor \bf { 2l + 2w }
We begin by finding the greatest common factor (GCF):
Rewrite each term using the GCF (2) = 2:
Factor out 2:
Perfect Square Trinomial
- 𝑎2 + 2 𝑎b + b2 = ( 𝑎 + b)2
- 𝑎2 + 2 𝑎b + b2 = ( 𝑎 - b)2
Factor \bf {x^2 + 16x + 64}
We begin by identifying the first and last terms as perfect squares:
Recognizing the square of a binomial formula (𝑎 - b)^2 = 𝑎^2 - 2𝑎b + b^2 , we check the middle term:
Since the middle term matches -2(8)(x), we apply the square of binomial formula:
Factor \bf{ 9𝑎^2 b^2 + 24𝑎^2bc + 16c^2}
We begin by identifying the first and last terms as perfect squares:
Recognizing the square of a binomial formula ( 𝑎 + b)2 = 𝑎2 + 2𝑎b2 + b2 , we check the middle term:
Since the middle term matches 2(3𝑎^2b) (4c), we apply the square of a binomial formula:
Factor \bf{\dfrac{1}{4}m^2 + \dfrac{1}{5}mn + \dfrac{1}{25}n^2}
We begin by identifying the first
Recognizing the square of a binomial formula ( 𝑎 + b)2 = 𝑎2 + 2𝑎b + b2, we check the middle term:
Difference of Two Squares:
- 𝑎2 - b2 = (𝑎 - b) (𝑎 + b)
Factor \bf { x^2 - 25}
We begin by expressing each term as squares:
Recognizing the difference of two squares formula 𝑎2 - b2 = (𝑎 - b) (𝑎 + b), we rewrite:
Apply the difference of squares formula:
Factor \bf{25x^2 - \dfrac{1}{4}y^2}
We begin by expressing each term as squares:
Recognizing the difference of two square formula 𝑎2 - b2 = (𝑎 - b)(𝑎 + b), we rewrite:
Apply the difference of square formula:
Factor \bf{9x^2 - 49}
We begin by expressing each term as squares:
Recognizing the difference of two squares formula 𝑎2 - b2 = (𝑎 - b) (𝑎 + b), we rewrite:
Appy the difference of squares formula:
Sum and Difference of Cubes:
- 𝑎3 + b3 = (𝑎 + b) (𝑎2 - 𝑎b + b2)
- 𝑎3 - b3 = (𝑎 + b) (𝑎2 - 𝑎b + b2)
Factor \bf{x^3 + 64y^3}
We begin by expressing each term as cubes:
Recognizing the sum of cubes formula: 𝑎3 + b3 = (𝑎 + b) (𝑎2 - 𝑎b + b2), we identify:
Apply the sum of cubes formula:
Factor \bf{64r^3 - 729s^3}
We begin by expressing each term as cubes:
Recognizing the difference of cubes formula: 𝑎3 - b3 = (𝑎 -b) (𝑎2 + 𝑎b +b2), we identify:
Apply the difference of cubes formula:
Factor \bf {125x^6 + 8y^9}
We begin by expressing each term as cubes:
Recognizing the sum of cubes formula: 𝑎3 + b3 = ( 𝑎 + b) ( 𝑎2 - 𝑎b + b2), we identify:
Apply the sum of cubes formula:
To factor expressions completely, here are some steps you must follow:
- Start with factoring by greatest common monomial factor, if possible.
- If both the exponents are even, the constants are perfect squares, and in the form of subscription, it is factorable by difference of two squares.
- Similarly, if the exponents are multiples of 3, the constant are perfect cubes, then it is factorable by sum/difference of two cubes.
- If there are three terms present, evaluate if it is a perfect square trinomial.
If the expression cannot be factored by the previous techniques, perhaps it can be factored by grouping, or it is general quadratic expression, which will be discussed in the next module.
Factor \bf{16x^4 - 250x}
We begin by finding the greatest common factor (GCF):
The GCF is 2x, so we factor it out:
Next, recognize that 8x3 - 125 is a difference of cubes:
Using the difference of cubes formula:
Apply the formula:
Substituting back, we get:
Final factored form:
Factor \bf{2x^2 - 32}
We begin by finding the greatest common factor (GCF):
The GCF is 2, so we factor it out:
Next, recognize that x2 - 16 is a difference of two squares:
Applying this, we get:
Final factored form: