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Chapter 5: Problem 18
Factor completely. $$ 8 a^{3}+1 $$
Short Answer
Expert verified
(2a + 1)(4a^2 - 2a + 1)
Step by step solution
01
Identify the expression as a sum of cubes
Recognize that the expression is a sum of cubes, which can be factored using the formula for the sum of cubes: a^3 + b^3 = (a + b)(a^2 - ab + b^2)Here, 8a^3 can be written as (2a)^3 and 1 as 1^3.
02
Apply the sum of cubes formula
Using the formula a^3 + b^3 = (a + b)(a^2 - ab + b^2), identify a = 2a and b = 1. Substitute these into the formula: (2a)^3 + (1)^3 = (2a + 1)((2a)^2 - (2a)(1) + (1)^2)
03
Simplify the factors
Expand and simplify the terms inside the parentheses: (2a)^2 = 4a^2(2a)(1) = 2a(1)^2 = 1Therefore, the expression becomes: (2a + 1)(4a^2 - 2a + 1)
Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Sum of Cubes
The sum of cubes is a specific type of expression in algebra. It looks like this: a^3 + b^3. In simpler terms, it involves adding the cubes of two numbers.
It's helpful to recognize this form because it has a straightforward factoring formula: \( a^3 + b^3 = (a + b)(a^2 - ab + b^2) \).
Understanding this pattern will make it easier to factor algebraic expressions effectively. Identifying the sum of cubes early on can save you time and effort in solving polynomial equations.
For instance, if you have 8a^3 + 1, break it down into cubes: 8a^3 is (2a)^3 and 1 is 1^3. Once identified, you can apply the formula.
Polynomial Factoring
Factoring polynomials is a crucial skill in algebra. It involves breaking down a polynomial into simpler 'factor' polynomials whose product equals the original polynomial.
Polynomials come in various forms, like a sum of cubes, which we see with 8a^3 + 1.
When factoring polynomials, always look for patterns and identities, such as the sum of cubes formula. This helps simplify expressions and solve equations more easily.
In the example of 8a^3 + 1, we first recognized it as a sum of cubes and then used the formula: \( (a + b)(a^2 - ab + b^2) \). This results in (2a + 1)(4a^2 - 2a + 1).
Remember: Practice makes perfect! The more you practice identifying and factoring different forms, the more skilled you become.
Algebraic Identities
Algebraic identities are powerful tools in algebra. They provide standard forms to recognize and simplify expressions.
One important identity is the sum of cubes formula: \( a^3 + b^3 = (a + b)(a^2 - ab + b^2) \).
These identities help in transforming complicated expressions into manageable forms. Take 8a^3 + 1, for example. We identified it as (2a)^3 + (1)^3. By recognizing this, we quickly applied the sum of cubes identity to simplify: (2a + 1)(4a^2 - 2a + 1).
Mastering algebraic identities is essential for success in algebra. They offer shortcuts and deeper understanding of problems, making solutions more accessible.
Intermediate Algebra
Intermediate algebra builds on basic algebra and prepares you for advanced math topics. It involves more complex factoring, working with polynomials, and applying identities.
Context, such as recognizing forms like sums of cubes, becomes integral. For the expression 8a^3 + 1, intermediate algebra techniques helped us break it down and factor it: (2a)^3 + (1)^3.
By intermediate level, aim to be comfortable using formulas, identities, and systematic approaches to solving equations. In simpler terms, understand the 'why' behind steps.
This example with sum of cubes showcases how deeper understanding aids problem-solving. Practicing and reinforcing these concepts prepares you for higher-level math challenges.
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