Chapter 6: Problem 67
Factor each binomial completely. \(125 a^{4}-64 a b^{3}\)
Short Answer
Expert verified
The complete factorization is: \(a(5a - 4b)(25a^2 + 20ab + 16b^2)\).
Step by step solution
01
Identify the Common Factor
First, verify if there is a common factor in both terms of the binomial. We have the terms: \(125a^4\) and \(64ab^3\). The greatest common factor between these terms is \(a\).
02
Factor Out the Greatest Common Factor
Factor out the common factor \(a\) from each term. The expression becomes: \[a(125a^3 - 64b^3)\].
03
Recognize a Difference of Cubes
Observe that the expression \(125a^3 - 64b^3\) is a difference of cubes since \(125a^3 = (5a)^3\) and \(64b^3 = (4b)^3\).
04
Apply the Difference of Cubes Formula
For a difference of cubes \(x^3 - y^3\), use the formula \(x^3 - y^3 = (x-y)(x^2 + xy + y^2)\). Here, let \(x = 5a\) and \(y = 4b\).
05
Write the Factored Form
Substitute \(x\) and \(y\) into the formula to get: \((5a - 4b)((5a)^2 + (5a)(4b) + (4b)^2)\), which simplifies to \((5a - 4b)(25a^2 + 20ab + 16b^2)\).
06
Combine with the Greatest Common Factor
Finally, include the factor \(a\) factored out earlier. The fully factored form of the original expression is: \[a(5a - 4b)(25a^2 + 20ab + 16b^2)\].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Common Factor
In algebra, identifying the common factor in a binomial is usually the first step in the factoring process. The common factor is a term that divides each part of the binomial without leaving a remainder, essentially simplifying it. To find the common factor of a binomial like \(125a^4 - 64ab^3\), you start by looking at each term of the binomial separately.
- "125a^4" and "64ab^3" are two terms which both include "a" as a factor.
- By extracting the common factor, \(a\), you are left with \(125a^3 - 64b^3\).
Difference of Cubes Formula
When factoring binomials, recognizing special algebraic forms can significantly simplify the process. One such form is the difference of cubes. A difference of cubes is an expression like \(x^3 - y^3\), which represents the subtraction of one cube from another.
For example, \(125a^3 - 64b^3\) can be seen as a difference of cubes, where \(125a^3\) equals \((5a)^3\) and \(64b^3\) equals \((4b)^3\).
The difference of cubes formula is given by:
For example, \(125a^3 - 64b^3\) can be seen as a difference of cubes, where \(125a^3\) equals \((5a)^3\) and \(64b^3\) equals \((4b)^3\).
The difference of cubes formula is given by:
- \(x^3 - y^3 = (x-y)(x^2 + xy + y^2)\)
- \((5a - 4b)((5a)^2 + (5a)(4b) + (4b)^2)\)
Algebraic Expressions
Algebraic expressions are composed of variables, coefficients, and constants that are combined using operations like addition, subtraction, multiplication, and division. When working with expressions such as \(125a^4 - 64ab^3\), understanding their structure is essential for successful manipulation and simplification.
In this case, the combination of terms \(125a^4\) and \(-64ab^3\) form a binomial separated by a minus sign, indicating subtraction. Factoring expressions often involves breaking them into simpler parts to reveal underlying relationships or patterns.
In this case, the combination of terms \(125a^4\) and \(-64ab^3\) form a binomial separated by a minus sign, indicating subtraction. Factoring expressions often involves breaking them into simpler parts to reveal underlying relationships or patterns.
- First, we look for the greatest common factor (GCF) that simplifies the expression by pulling out similar factors, which here is \(a\).
- Next, by recognizing that the expression is a difference of cubes, applying the difference of cubes formula further dissects the problem into manageable portions.