Chapter 7: Problem 18
Find the product. $$ \frac{x^2-x-6}{4 x^3} \cdot \frac{2 x^2+2 x}{x^2+5 x+6} $$
Short Answer
Expert verified
The product of the given fractions is thus simplified to \( \frac{(x-3)(x+1)}{2x (x+3)} \).
Step by step solution
01
Factorize the Quadratic Expressions
Factorize the quadratic expression \(x^2 - x - 6\) in the numerator of the first fraction and the quadratic expression \(x^2 + 5x + 6\) in the denominator of the second fraction in order to express them as product of binomials. The first expression can be factored into \((x-3)(x+2)\) and the second expression into \((x+2)(x+3)\).
02
Express Fractions with Factored Expressions
Substitute the factored expressions into the fractions. The given expression can therefore be written as: \[\frac{(x-3)(x+2)}{4 x^3} \cdot \frac{2 x(x+1)}{(x+2)(x+3)}\]
03
Simplify the Fractions
Simplify the fractions by cancelling out common factors in the numerator and the denominator. The \(x+2\) terms in the numerator of the first fraction and the denominator of the second fraction will cancel each other out. Thus, the simplified product will be:\[\frac{(x-3)2x(x+1)}{4 x^3 (x+3)}\]
04
Further Simplify
To further simplify, factorize \(2x\) in the numerator and \(4x^3\) in the denominator to cancel out common factors:\[\frac{x(x-3)(x+1)}{2 x^2 (x+3)}\]This reduces to:\[\frac{(x-3)(x+1)}{2x (x+3)}\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Factoring Quadratics
When you encounter quadratic expressions like \( x^2 - x - 6 \) or \( x^2 + 5x + 6 \), the process of factoring them is essential in many mathematical operations like simplifying and solving equations. Quadratics can often be rewritten as a product of two binomial expressions. Here's how it works:
- Identify two numbers that multiply to give the constant term (the last number) and add to give the middle coefficient (the coefficient of \( x \)).
- For \( x^2 - x - 6 \), these numbers are \(-3\) and \(2\). Factoring results in \( (x-3)(x+2) \).
- For \( x^2 + 5x + 6 \), the numbers \(2\) and \(3\) are used, leading to \((x+2)(x+3)\).
Simplifying Fractions
Simplifying fractions in algebra involves canceling common terms in the numerator and the denominator. Here's a step-by-step approach:
- Ensure all parts of the fractions are factored completely. This means breaking down all polynomial expressions into their simplest binomial or monomial components.
- Identify any common factors in both the numerator and the denominator that can be canceled out. In the product \( \frac{(x-3)(x+2)}{4 x^3} \cdot \frac{2 x(x+1)}{(x+2)(x+3)} \), the \( x+2 \) terms cancel each other out.
- Simplification often results in a more manageable expression, reducing complexity and making further operations, like multiplication or division, easier to perform.
Polynomial Expressions
Polynomial expressions form the backbone of a lot of algebraic operations. Understanding how to manipulate them is crucial:
- A polynomial is simply the sum of terms, each consisting of a coefficient and a variable raised to a power, such as \( 2x^3 + 5x^2 + x + 6 \).
- Operations like addition, subtraction, and multiplication are intrinsic to working with polynomials. Factoring them, as seen in the quadratic expressions, can significantly simplify these operations.
- In the exercise, recognizing polynomials in both the fractions and utilizing their factored forms helps in multiplying and simplifying the entire expression efficiently.