Chapter 0: Problem 70
Factor the expression completely. $$ x^{3}+3 x^{2}-x-3 $$
Short Answer
Expert verified
The completely factored form of the expression is \((x + 3)(x - 1)(x + 1)\).
Step by step solution
01
Group Terms in Pairs
To simplify factorization, group terms into pairs: \[ (x^3 + 3x^2) + (-x - 3) \]
02
Factor Out the Greatest Common Factor from Each Pair
Factor out the greatest common factor (GCF) from each pair of terms. From the first pair \((x^3 + 3x^2)\), factor out \(x^2\), and from the second pair \((-x - 3)\), factor out \(-1\): \[ x^2(x + 3) - 1(x + 3) \]
03
Factor by Grouping
Notice the common factor \((x + 3)\) in both terms. Factor \((x + 3)\) out of the entire expression:\[ (x + 3)(x^2 - 1) \]
04
Factor the Difference of Squares
The expression \(x^2 - 1\) is a difference of squares, which can be factored as \((x - 1)(x + 1)\):\[ (x + 3)(x - 1)(x + 1) \]
05
Confirmation of Complete Factorization
Verify that the expression \((x + 3)(x - 1)(x + 1)\) is completely factored by expanding to ensure it matches the original expression \(x^3 + 3x^2 - x - 3\). The factorization is confirmed to be correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
The difference of squares is a special type of polynomial that can easily be factored. It follows the format
- n^2 - m^2
- (n - m)(n + m)
- difference of squares.
- \(x^2 -1\)
- \((x - 1)(x + 1)\)
Common Factor
Finding and factoring out the greatest common factor (GCF) is often the first step in polynomial factorization. The GCF is the largest factor that divides each term in a polynomial. By identifying it, you can simplify expressions considerably and make them easier to work with. In the exercise, we first examine a pair of terms:
- \((x^3 + 3x^2)\)
- \(x^2(x + 3)\)
- \((-x - 3)\)
- \(-1(x + 3)\)
Factor by Grouping
Factoring by grouping is an invaluable technique when dealing with four-term polynomials. It involves rearranging and grouping terms in a way that allows for simple factoring. In this exercise, we first rearrange the polynomial into pairs:
- \((x^3 + 3x^2) + (-x - 3)\)
- \(x^2(x + 3) - 1(x + 3)\)
- \((x + 3)\)
- \((x + 3)(x^2 - 1)\)
Algebraic Expressions
Algebraic expressions are combinations of numbers, variables, and operations. Understanding how to manipulate these forms is the groundwork of algebra. The given problem,
- \(x^{3}+3x^{2}-x-3\)