Chapter 1: Problem 55
Perform the addition or subtraction and simplify. $$\frac{2}{x}+\frac{3}{x-1}-\frac{4}{x^{2}-x}$$
Short Answer
Expert verified
The simplified expression is \(\frac{5x - 6}{x(x-1)}\).
Step by step solution
01
Identify Common Denominator
The first step is to find a common denominator for all three fractions. The denominators are \(x\), \(x-1\), and \(x^2-x\). Rewrite \(x^2-x\) as \(x(x-1)\). Thus, the common denominator is \(x(x-1)\).
02
Rewrite Each Fraction with Common Denominator
Convert each fraction to have the common denominator \(x(x-1)\): - For \(\frac{2}{x}\), multiply both numerator and denominator by \((x-1)\) to get \(\frac{2(x-1)}{x(x-1)}\).- For \(\frac{3}{x-1}\), multiply both numerator and denominator by \(x\) to get \(\frac{3x}{x(x-1)}\).- The fraction \(\frac{4}{x^2-x}\) is already with the denominator \(x(x-1)\).
03
Combine the Fractions
Now that all fractions have the same denominator, combine them into a single fraction:\[ \frac{2(x-1) + 3x - 4}{x(x-1)} \]
04
Simplify the Numerator
Expand and simplify the numerator:- Distribute the \(2\) in \(2(x-1)\) to get \(2x - 2\).- Add like terms in the numerator: \[ 2x - 2 + 3x - 4 = 5x - 6 \]
05
Write the Final Simplified Expression
Now the fraction is:\[ \frac{5x - 6}{x(x-1)} \]This is the simplified form since no common factors appear in the numerator and the denominator.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Common Denominator
When dealing with fraction addition and subtraction, finding a common denominator is crucial. This is similar to finding a common language that all fractions can understand. Without a common denominator, it's like trying to add apples and oranges - it just doesn't work easily.
- Each original fraction might have a different denominator, making direct addition or subtraction impossible.
- A common denominator is found by identifying the least common multiple (LCM) of the original denominators.
- In this exercise, the denominators were \(x\), \(x-1\), and \(x^2-x\), where \(x^2-x\) was rewritten as \(x(x-1)\).
Simplifying Expressions
After working the fractions into a single expression with a common denominator, the next challenge is simplifying the expression. Simplification requires careful handling of algebraic expressions to make them more digestible.
- Begin by expanding the expressions, meaning you'll open up terms like \(2(x-1)\) into \(2x - 2\).
- Combine like terms, which are terms that have the same variables raised to the same power. Here, you combine terms like \(2x\), \(3x\), and \(-4\) to get \(5x - 6\).
- Write this expression over the common denominator.
Algebraic Fractions
Algebraic fractions behave like numerical fractions but involve variables, introducing a layer of complexity. Understanding them is crucial for a firm grasp of many algebraic techniques and methods.
- Algebraic fractions can include any polynomial expressions in their numerators and denominators.
- Operations like addition and subtraction require a special focus on finding a common denominator, unlike straightforward numerical fractions.
- During calculations, always check that any simplification steps maintain the conditions for non-zero denominators to avoid undefined expressions.