Chapter 1: Problem 5
Express as a polynomial. $$(2 x+3 y)(2 x-3 y)$$
Short Answer
Expert verified
The polynomial is \(4x^2 - 9y^2\).
Step by step solution
01
Identify the expression form
The given expression is \((2x + 3y)(2x - 3y)\). This expression is in the form of \((a+b)(a-b)\) which is a difference of squares form.
02
Apply the difference of squares formula
The formula for the difference of squares is \((a+b)(a-b) = a^2 - b^2\). In this expression, we can identify \(a = 2x\) and \(b = 3y\).
03
Square the first term
Calculate \(a^2\), where \(a = 2x\). Thus, \((2x)^2 = 4x^2\).
04
Square the second term
Calculate \(b^2\), where \(b = 3y\). Thus, \((3y)^2 = 9y^2\).
05
Subtract the squared terms
Substitute the squared terms back into the formula: \(4x^2 - 9y^2\). This is the polynomial form of the expression.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Polynomial Expression
A polynomial expression is a mathematical phrase involving a sum of powers in one or more variables multiplied by coefficients. In simpler terms, it's like a string of terms added together. Each term is made up of:
- A coefficient (a constant number or multiplies with variables)
- A variable (like \(x\) or \(y\))
- An exponent (which tells you how many times the variable is used as a factor)
- \(4x^2\) is the first term, where 4 is the coefficient, \(x\) is the variable, and 2 is the exponent.
- \(-9y^2\) is the second term, with -9 as the coefficient, \(y\) the variable, and 2 as the exponent.
Factoring Polynomials
Factoring polynomials involves writing a polynomial as a product of simpler polynomials, much like breaking down a number into its prime factors. This process is essential in solving equations and simplifying expressions. There are different methods for factoring:
- Common Factors: Identify and pull out common factors from terms. For instance, in \(2x^2 + 4x\), you can factor out \(2x\) giving \(2x(x + 2)\).
- Grouping: Used typically when a polynomial has four terms. Terms are regrouped to find common factors.
- Difference of Squares: This technique is ideal for expressions like \((a+b)(a-b)\). This type of factoring involves recognizing a pattern where a squared term is subtracted from another squared term, simplifying to \(a^2 - b^2\).
Algebraic Identities
Algebraic identities are equations that hold true for any value of the variables. One such identity is the difference of squares, given by \((a+b)(a-b) = a^2 - b^2\). This is one of the most commonly used identities in algebra.These identities help simplify expressions and solve equations quickly. The expression \((2x + 3y)(2x - 3y)\) is a perfect instance where this identity plays a vital role. By recognizing it fits the pattern \((a+b)(a-b)\), we can directly simplify it to \(4x^2 - 9y^2\), saving time and effort in calculations.Here’s a brief recap of why knowing algebraic identities is beneficial:
- Simplification: They reduce complex expressions into simpler forms, making them easier to work with.
- Problem Solving: Use these identities to quickly identify equivalences in equations.
- Insight: Understanding these identities helps gain deeper insight into algebraic manipulations.