Chapter 1: Problem 48
Perform the addition or subtraction and simplify. $$\frac{x}{x^{2}-x-6}-\frac{1}{x+2}-\frac{2}{x-3}$$
Short Answer
Expert verified
Simplified expression is \( \frac{-2x - 1}{(x-3)(x+2)} \).
Step by step solution
01
Factor the Quadratic Denominator
The expression is \( \frac{x}{x^{2}-x-6} \). Our task is to factor this quadratic: \( x^2 - x - 6 \). We find two numbers that multiply to \(-6\) and add to \(-1\). These numbers are \(-3\) and \(2\). So, \( x^2 - x - 6 = (x-3)(x+2) \).
02
Rewrite the Expression with Common Denominator
The common denominator of the fractions \( \frac{x}{(x-3)(x+2)} - \frac{1}{x+2} - \frac{2}{x-3} \) is \((x-3)(x+2)\). We rewrite each fraction with this common denominator: \[ \frac{x}{(x-3)(x+2)} - \frac{1 \cdot (x-3)}{(x+2)(x-3)} - \frac{2 \cdot (x+2)}{(x-3)(x+2)} \].
03
Combine the Fractions
Now that each fraction has the common denominator \((x-3)(x+2)\), we combine the numerators: \[ \frac{x - (x-3) - 2(x+2)}{(x-3)(x+2)} \]. First, distribute the \(-1\) and \(-2\) in the numerators.
04
Simplify the Numerator
Simplify the numerator of the combined fraction: \( x - x + 3 - 2x - 4 = -2x + 3 - 4 = -2x - 1 \). Thus, the expression becomes \( \frac{-2x - 1}{(x-3)(x+2)} \).
05
Present the Simplified Expression
Since no further simplification of \( \frac{-2x - 1}{(x-3)(x+2)} \) is possible due to no common factors existing between the numerator and denominator, this is the final simplified expression.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Factorization
Quadratic factorization is a fundamental process in algebra that involves breaking down a quadratic expression into simpler, multiplying expressions, called factors. This process is essential for solving equations and simplifying expressions. To factor a quadratic like \( x^2 - x - 6 \), we look for two numbers that multiply to give the constant term (in this case, \(-6\)) and add to give the linear coefficient (\(-1\)). After some trials, we find these numbers to be \(-3\) and \(+2\). This means we can write the quadratic as
- \((x - 3)(x + 2)\),
Common Denominator
When working with multiple fractions that involve polynomials, having a common denominator is key to adding or subtracting them. A common denominator is a shared multiple of the denominators of all the fractions in the expression. In this exercise, we have fractions with denominators \((x-3)(x+2)\), \(x+2\), and \(x-3\). The common denominator involves combining the unique factors from each of these:
- \((x-3)(x+2)\).
Fraction Simplification
Simplifying fractions is the final step in making rational expressions as concise as possible. Once we've rewritten each fraction with a common denominator, as in our original problem, simplifying involves merging the numerators into a single expression. This means:
- Performing all subtraction and addition operations within the numerators.