# Factoring Polynomials

## Simplifying Polynomials: A Guide to Factoring

When it comes to solving polynomials, there's a helpful trick that can cut down on confusion and make the process much easier: factoring. By finding common patterns and simplifying expressions, we can solve equations more efficiently. In this article, we'll explore the concept of factoring polynomials, from its definition to real-life examples.

## Understanding Factoring

To begin, let's define factoring. Simply put, factoring involves writing a number or expression as a product of its factors. This is a crucial concept when dealing with complex polynomials. Let's see it in action with an example:

Factor the value of 20.

### Solution:

There are multiple ways to break down the number 20, but for our purposes, 2 x 2 x 5 is the most simplified form.

When it comes to algebra, factoring a polynomial means rewriting it as a product of lower degree polynomials. In other words, it's the reverse of the FOIL method. Just as a reminder, the FOIL method is used to multiply two binomials (a + b)(c + d), where FOIL stands for First, Outer, Inner, Last.

Instead of expanding a polynomial, we can use factoring to represent it as a product of its lowest degree polynomials. Before we dive in, let's review some key definitions:

• A monomial is a polynomial with only one term, such as 2x.
• A binomial is a polynomial with two terms, like 3x + 1.
• A trinomial has three terms, such as x + 2y + 5.

## The Importance of Factoring

Factoring is critical for simplifying expressions and solving equations efficiently. It also helps us understand the behavior of a polynomial in graphing scenarios and identify solutions to polynomial equations. In this section, we will focus on:

• Factoring a polynomial
• Solving polynomial equations through factoring

Now, let's explore the three main methods of factoring.

## 1. Greatest Common Factor (GCF)

The Greatest Common Factor (GCF) is the largest monomial that can be divided from all terms in a polynomial. Starting with this method is crucial, as it simplifies the numbers we're working with and makes the process much easier.

To use this method, we first identify the GCF and then factor it out of the polynomial. In essence, we're reversing the distributive law, which can be written as:

In general, factoring polynomials using the GCF can be done as follows:

Note that the left side of this general form contains the common factor ab. Let's look at some examples to see how this method works:

Factor the following expression by finding the GCF:

### Solution:

We can factor out 5 and x2 from each term to get:

Factor the following expression by finding the GCF:

### Solution:

Each term in the expression contains both x3 and y, which we can factor out to get:

Factor the following expression by finding the GCF:

### Solution:

First, we can factor out the binomial (2x + 7) to get:

Next, we can take out 3x from (9x2 - 12x) to get the final factored form:

Try using the FOIL method to verify these factored results. Do they match up?

A polynomial with a degree of 2 is known as a quadratic. This means that the largest exponent in the polynomial is 2. The next method we'll cover is specific to quadratics.

## Factoring Quadratic Trinomials Using the Trial and Error Method

Quadratic trinomials are polynomials with three terms, commonly taking the form of ax2 + bx + c. To factor these expressions, we use the trial and error method to break them down into a product of first-degree binomials. This requires some experimentation, but with practice, it becomes easier and faster to do so.

## The Five Steps to Factor Quadratic Trinomials

Factoring quadratic trinomials may seem intimidating, but by following these five simple steps, you can easily master this method:

• Step 1: Begin by writing down a pair of parentheses: ( ) ( )
• Step 2: Multiply the first term in the trinomial with the binomials to get the following expression: (x )(x )
• Step 3: Find factors of the third term of the trinomial that can be combined to form the middle term. These should be in the form of a pair, such as (1 )(12 ) or (-3 )(4 ).
• Step 4: Utilize trial and error to determine which pair of factors fits the polynomial. Be sure to try all possible pairs and orders to find the correct values.
• Step 5: Once you have identified the correct pair, plug in the values to obtain the complete factorized form.

Remember, practice makes perfect when it comes to mastering this method. You can also use the general formula below to factor quadratic trinomials:

## Example 1:

Factorize the polynomial: x2 + x – 12

Solution:

Step 1 and 2: The first term, x2, can be factored as (x )(x ).

Step 3: We need to find a pair of numbers that multiply to get -12 and add to get 1. After trying out all the factors (-1 )(12 ), (1 )(-12 ), (-2 )(6 ), (2 )(-6 ), (-3 )(4 ), and (3 )(-4 ), we find that the pair (-3 )(4 ) satisfies the polynomial.

Step 4: Plugging in the values, we get (x – 3 )(x + 4 ).

Remember: Be sure to try all possible pairs and orders when using the trial and error method.

## Example 2:

Factorize the polynomial: 3x2 + 11x – 10

Solution:

Step 1 and 2: The first term, 3x2, can be factored as (3x )(x ).

Step 3: We need to find a pair of numbers that multiply to get -10 and add to get 11. After trying out all the factors (-1 )(10 ), (1 )(-10 ), (-2 )(5 ), and (2 )(-5 ), we find that the pair (2 )(5 ) satisfies the polynomial.

Step 4: Plugging in the values, we get (3x + 2 )(x + 5 ).

## Example 3:

Factorize the polynomial: x2 + 2x – 8

Solution:

Step 1 and 2: The first term, x2, can be factored as (x )(x ).

Step 3: We need to find a pair of numbers that multiply to get -8 and add to get 2. After trying out all the factors (-1 )(8 ), (1 )(-8 ), (-2 )(4 ), and (2 )(-4 ), we find that the pair (-2 )(4 ) satisfies the polynomial.

Step 4: Plugging in the values, we get (x – 2 )(x + 4 ).

## Factor Quadratic Trinomials Using the Grouping Method

Another effective method for factoring quadratic trinomials is the grouping method, which is particularly useful when dealing with polynomials with four terms. Let's take a look at the three simple steps involved:

• Step 1: Group the polynomial into two sets of two terms by separating the first two terms and the last two terms.
• Step 2: Factorize each group using the GCF (Greatest Common Factor) method.
• Step 3: If there is a common binomial between the two groups, factor it out using the GCF method again.

The general formula for factoring quadratic trinomials using the grouping method is:

## Example 1:

Factorize the polynomial: x2 + 2x – 42

Solution:

Step 1: Grouping the first two terms and last two terms, we get (x2 + 2x ) – (42 ).

Step 2: Factoring out 2x from the first group and -21 from the second group, we get 2x(x + 1 ) – 21(x + 1 ).

Step 3: We can now factor out the common binomial (x + 1 ), giving us the final factorized form: (x + 1 )(2x - 21 ).

## Example 2:

Factorize the polynomial: x3 + 9x2 + 22x + 12

Solution:

Step 1: Grouping the first two terms and last two terms, we get (x3 + 9x2 ) + (22x + 12 ).

Step 2: Factoring out x2 from the first group and 2 from the second group, we get x2(x + 9 ) + 2(11x + 6 ).

Step 3: We can now factor out the common binomial (x + 9 ), giving us the final factorized form: (x + 9 )(x2 + 2 ).

## Master the Grouping Method for Factoring Quadratic Trinomials

Factoring 3-term polynomials may seem challenging, but with the grouping method, this task becomes much more straightforward and efficient.

If you've ever struggled with factoring polynomials, you're not alone. But fear not! There is an easy method for solving these types of equations. This method involves finding a common binomial in the polynomial and factoring it out, followed by grouping the remaining terms in a specific way.

Let's take a look at an example to better understand this method:

Say we have the polynomial expression x3 - 8x2 - x + 8. To factorize this, we can use the trial and error method to find two numbers that add up to -1 and multiply to get -8, the values of a and c. This turns the polynomial into a 4-term one, making it easier to factorize.

Next, we apply the grouping method by grouping the first two terms and the last two terms, allowing us to factor out x from the first group and -8 from the second group. Finally, we observe that both groups have a common binomial, (x-1), which we can factor out to obtain the final answer: (x-1)(x-8).

## Factoring Polynomials of Higher Degree

So far, we have only dealt with polynomials of degree two. But what happens when we need to factorize polynomials of higher degrees? While there is no specific method for this, we can still use the techniques we have learned in this lesson.

It is crucial to master these factoring methods, as they can help us spot common patterns when solving more complex expressions. Let's look at some examples to solidify our understanding:

### Example 1:

Suppose we have the polynomial expression x4 - 2x3 + x2 - 2. To fully factorize this, we first notice that we can factor out x3 from each term, leaving us with (x-1)(x-2). From the first term, we can see that the factored form will take the structure of (x-1). To find the missing numbers, we need a pair that multiplies to get -2 and adds up to -3. Utilizing some trial and error, we find the pair (-1)(2) that satisfies this criterion, giving us the final answer: (x-1)(x-1)(x-2).

### Example 2:

Another example is x3 - 8x2 - 5x + 40. By using the grouping method, we can group the first two terms and the last two terms, factorizing out x2 and -5 respectively. This gives us the common factor of (x-4) in both groups, allowing us to factorize it out and obtain (x-4)(x-5). But we're not finished yet! Notice that we have the perfect square binomial (x-4)(x-4), which we can further simplify to get the final answer: (x-4)(x-4)(x-5).

## Solving Polynomial Equations with Ease

Now that we have mastered factoring polynomials, we can move on to solving them. For example, let's say we have the standard form of a polynomial equated to zero: x3 - 3x2 - x + 3 = 0. As we have learned, the factorized form of this polynomial is (x-1)(x-3). Utilizing the Zero Product Property, we know that the product of the two factors is zero if at least one of them is zero. Therefore, we can set each factor equal to zero and solve for x, giving us the solutions x=1 and x=3.

## The Power of the Zero Product Property in Factoring Polynomials

When it comes to working with polynomials, one essential property to remember is the Zero Product Property. This mathematical property is incredibly helpful in solving equations and understanding its role in factoring polynomials can greatly simplify the process. Let's take a closer look at the Zero Product Property and how it can be applied.

The Zero Product Property states that if ab=0, then a=0 or b=0 (or both a=0 and b=0). This means that when multiplying two numbers, if the product is equal to 0, then at least one of the numbers must be 0. While this may seem like a simple concept, it can make a significant difference in solving equations and finding the x-intercepts of a graph for a given polynomial.

When solving a factored polynomial using the Zero Product Property, we can identify the solutions by rearranging and solving for x, resulting in typically two solutions. This is because the factored form of a polynomial is usually written as a product of two factors. This property is crucial to understand when it comes to factoring polynomials and solving equations.

In summary, factoring polynomials involves finding a common binomial and grouping remaining terms, while the Zero Product Property is an essential tool in solving these equations. By mastering these techniques and understanding their applications, factoring polynomials is no longer a daunting task.

## Using Zero Product Property to Find Solutions to Polynomials

Let's explore how to find solutions to polynomials using the Zero Product Property. This property is a valuable tool that helps simplify expressions and solve equations. To understand its impact, let's consider an example polynomial and find its solutions.

Given the polynomial below, we can see that its factorized form is: x-3=0 or x+2=0 or x-1=0. Applying the Zero Product Property, we can solve for x and obtain three real roots: x=3, x=-2, or x=1. These solutions are also the x-intercepts of the graph for this polynomial.

Now, let's try another example to see how this property works with polynomials that have more terms. In this case, we have a polynomial with four terms and its factorized form is: x+1=0 or x-2=0 or x+3=0 or x-4=0. Applying the Zero Product Property, we can solve for x and obtain four real roots: x=-1, x=2, x=-3, or x=4. These solutions are again the x-intercepts of the graph for this polynomial.

We can also use the Zero Product Property to zoom into the x-intercepts of a graph and better visualize the solutions. Take the example of a polynomial with four terms again, but this time we will focus on the x-intercepts. We can see that the x-intercepts are located at x=-1, x=2, x=-3, and x=4, just as our solutions predicted.

It's important to note that when solving repeated factor equations, we will only obtain one solution. For instance, in this polynomial, we will only get one real solution of x=0. The graph also confirms this with only one x-intercept at x=0.

## Key Takeaways: Factoring Polynomials

• Factoring a polynomial means rewriting it as a product of lower degree polynomials.
• This process greatly helps in simplifying an expression.
• The Zero Product Property is a useful tool in solving factored polynomials, where the solutions are also the x-intercepts of the graph.
• We can factor polynomials in different ways, including by finding the greatest common factor, using the grouping method, and identifying quadratic trinomials.
• The linear factors of a polynomial are first-degree polynomials that make up the product of a higher degree polynomial.

To sum up, understanding the Zero Product Property and its application in factoring polynomials is crucial in solving equations and interpreting the graph of a polynomial. By familiarizing yourself with factoring techniques, you can simplify this process and obtain accurate results. Keep practicing and happy factoring!