Chapter 6: Problem 39
Factor. $$ 64 x^{3}-27 y^{3} $$
Short Answer
Expert verified
The factored form is \((4x-3y)(16x^2 + 12xy + 9y^2)\).
Step by step solution
01
Identify the Form of the Expression
The given expression is a binomial with two terms: \(64x^3\) and \(27y^3\). We notice that both terms are perfect cubes.
02
Recognize the Formula for a Difference of Cubes
The formula for factoring a difference of cubes is \(a^3 - b^3 = (a-b)(a^2 + ab + b^2)\). Our goal is to rewrite \(64x^3 - 27y^3\) in this form.
03
Identify \(a\) and \(b\) in the Difference of Cubes Formula
In the expression \(64x^3\), the cube root is \((4x)^3\), hence \(a = 4x\). In the term \(27y^3\), the cube root is \((3y)^3\), so \(b = 3y\).
04
Substitute \(a\) and \(b\) into the Difference of Cubes Formula
Substitute \(a = 4x\) and \(b = 3y\) into the formula: \[(4x-3y)((4x)^2 + (4x)(3y) + (3y)^2)\].
05
Simplify the Resulting Expression
Simplify each part of the expression:1. \((4x)^2 = 16x^2\)2. \((4x)(3y) = 12xy\)3. \((3y)^2 = 9y^2\).Thus, the expression becomes \((4x-3y)(16x^2 + 12xy + 9y^2)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding Binomials
In algebra, a **binomial** is a type of polynomial that consists of exactly two terms. These terms are connected by either a plus or a minus sign. Binomials are very common in algebraic expressions and are a critical concept to understand when learning polynomial arithmetic. Consider the example:
- The expression \(64x^3 - 27y^3\) is a binomial because it contains two distinct terms: \(64x^3\) and \(-27y^3\).
- The terms in a binomial can involve variables raised to a power, as well as coefficients (numbers multiplying the variables).
Recognizing Perfect Cubes
A **perfect cube** is a number that can be expressed as the cube of an integer or a variable raised to the third power. Perfect cubes are essential in algebra, particularly when dealing with the difference of cubes or sum of cubes.For instance:
- The number 64 is a perfect cube because it equals \(4^3\).
- Similarly, the term \(x^3\) is a perfect cube since it is \((x)^3\).
- For the expression \(64x^3\), \(4x\) is the base that when cubed gives the term: \((4x)^3 = 64x^3\).
Working with Algebraic Expressions
**Algebraic expressions** are mathematical phrases that can include numbers, variables, and operation symbols. They form the foundation of algebra and are used for modeling real-world situations, solving equations, and more.Key points to understand:
- Algebraic expressions can range from simple monomials like \(3x\) to complex polynomials like \(64x^3 - 27y^3\).
- These expressions can be manipulated in various ways, such as by factoring, which involves expressing the equation as a product of its factors.
- When working with algebraic expressions, especially those involving perfect cubes and binomials, understanding and applying the appropriate formulas (like factoring the difference of cubes) becomes crucial.