How to Factor by GCF?

Related Topics

• How to Factor Polynomials?

Step-by-step guide to factoring by \(GCF\)

The process of factoring polynomials includes expressing the polynomial as a product of its factors. Factoring polynomials helps to find the zeros of the polynomial expression or to find the values of the variables of the given expression.

There are several methods for factoring polynomials based on expressions. One of them is factoring based on the greatest common factor or \(GCF\). The \(GCF\) of a polynomial is the greatest monomial that divides the polynomial terms. Note that the \(GCF\) should be a factor of all terms in the polynomial.

The process of obtaining the greatest common factor for two or more terms involves two simple steps. First, divide each expression into its prime factors, and then take as many common factors as possible from the given expressions.

Let us understand this using a simple expression of two terms \(15x^4 + 3x^3\). Here we split the terms into their prime factors \(15x^4 + 3x^3 = 5\times 3\times x\times x\times x\times x + 3\times x\times x\times x\). From these two terms, we can take the maximum common terms to get the greatest common factor. Here we have the maximum common factor as \(3x^3\), and hence \(15x^4 + 3x^3= 3x^3(5x + 1)\).

Factoring by \(GCF\) – Example 1:

Factor the polynomial. \(12y^3-27y^2\)

Solution: First, find the \(GCF\) of all of the terms:

\(12y^3=2×2×3×y×y×y\) , \(27y^2=3×3×3×y×y\). The common factors are \(3×y×y\). And, the \(GCF\) is \(3y^2\).

So \(12y^3-27y^2 = 3y^2(4y-9)\).