Chapter 1: Problem 66
Factor the expression by grouping terms. $$x^{5}+x^{4}+x+1$$
Short Answer
Expert verified
The expression factors to \((x^4 + 1)(x + 1)\).
Step by step solution
01
Recognize the expression
The expression to be factored is \(x^5 + x^4 + x + 1\). This polynomial has four terms which suggests that factoring by grouping might be a suitable method.
02
Group terms
Group the terms in pairs that may yield a common factor: \((x^5 + x^4) + (x + 1)\).
03
Factor out the greatest common factor from each group
In the first group \((x^5 + x^4)\), the greatest common factor is \(x^4\), so factor it out: \(x^4(x + 1)\). In the second group \((x + 1)\), the common factor is \(1\), so rewrite it as \(1(x + 1)\). This results in \(x^4(x + 1) + 1(x + 1)\).
04
Factor out the common binomial factor
Now, notice that \((x + 1)\) is common in both grouped terms. Factor \((x + 1)\) out to get \((x^4 + 1)(x + 1)\).
05
Final check
Verify that the factored form \((x^4 + 1)(x + 1)\) expands back to the original expression \(x^5 + x^4 + x + 1\). When expanded, the expression indeed returns to the original.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Expressions
Polynomial expressions are mathematical phrases containing a sum of terms. These terms are made up of variables raised to whole number powers and coefficients. For example, in the expression \(x^5 + x^4 + x + 1\), each term includes a power of \(x\) with a specific coefficient. Here:
Understanding the structure of polynomials helps in identifying when and how to employ different factoring methods like factoring by grouping.
- \(x^5\) has a coefficient of 1.
- \(x^4\) also has a coefficient of 1.
- The stand-alone \(x\) has a coefficient of 1 as well.
- The constant term 1 is essentially \(x^0\) with a coefficient of 1.
Understanding the structure of polynomials helps in identifying when and how to employ different factoring methods like factoring by grouping.
Common Factors
A common factor in a polynomial expression is a number or variable that divides all parts of an expression evenly. Recognizing common factors is an essential skill when working with polynomials.
In the example of \(x^5 + x^4 + x + 1\), we start by grouping the terms to make finding a common factor easier. The terms \(x^5 + x^4\) share a common factor of \(x^4\), while \(x + 1\) does not share any variable factor, but can be considered as having a common factor of 1.
This results in:
In the example of \(x^5 + x^4 + x + 1\), we start by grouping the terms to make finding a common factor easier. The terms \(x^5 + x^4\) share a common factor of \(x^4\), while \(x + 1\) does not share any variable factor, but can be considered as having a common factor of 1.
This results in:
- Grouping \(x^5 + x^4\) as \(x^4(x + 1)\).
- Grouping \(x + 1\) as \(1(x + 1)\).
Factoring Techniques
Factoring is a fundamental process in algebra that reverses the distribution of terms with shared factors. Factoring by grouping is an efficient technique often used when an expression has four terms like \(x^5 + x^4 + x + 1\).
The key stages include:
The key stages include:
- First, split the expression into groups: \((x^5 + x^4) + (x + 1)\).
- Next, extract the greatest common factor from each group.
- Identify the common binomial factor \((x+1)\) that appears in each group.
- Then, factor \((x + 1)\) out of the expression to get \((x^4 + 1)(x + 1)\).