Chapter 5: Problem 13
Find all complex solutions for each equation by hand. $$\frac{2 x}{x^{2}-1}=\frac{2}{x+1}-\frac{1}{x-1}$$
Short Answer
Expert verified
The solution is \(x = -3\).
Step by step solution
01
Find a common denominator
To solve the equation \(\frac{2 x}{x^{2}-1}=\frac{2}{x+1}-\frac{1}{x-1}\), we first recognize that \(x^2 - 1\) can be factored as \((x-1)(x+1)\). Therefore, the common denominator for the entire equation is \((x-1)(x+1)\). We will use this to rewrite each term under a common denominator.
02
Rewrite the equation using the common denominator
Rewrite each fraction using the common denominator:- The left side becomes \(\frac{2x}{(x-1)(x+1)}\).- The right side's first fraction is \(\frac{2(x-1)}{(x-1)(x+1)}\).- The right side's second fraction is \(\frac{1(x+1)}{(x-1)(x+1)}\).Thus, the equation becomes: \[ \frac{2x}{(x-1)(x+1)} = \frac{2(x-1)}{(x-1)(x+1)} - \frac{1(x+1)}{(x-1)(x+1)} \].
03
Combine the right side
Combine the fractions on the right side over the common denominator:\[ \frac{2(x-1) - (x+1)}{(x-1)(x+1)} = \frac{2x - 2 - x - 1}{(x-1)(x+1)} = \frac{x - 3}{(x-1)(x+1)} \].Now the equation is:\[ \frac{2x}{(x-1)(x+1)} = \frac{x - 3}{(x-1)(x+1)} \].
04
Clear the denominators
Since both sides of the equation now have the same denominator, we can set the numerators equal to each other:\(2x = x - 3\).
05
Solve for x
Isolate \(x\) by subtracting \(x\) from both sides:\(2x - x = -3\)This simplifies to:\(x = -3\).
06
Verify the solution
Substitute \(x = -3\) back into the original equation to check for any extraneous solutions:- Left side: \(\frac{2(-3)}{(-3)^2-1} = \frac{-6}{8}\).- Right side: \(\frac{2}{-2} - \frac{1}{-4} = -1 + \frac{1}{4} = -\frac{3}{4}\).Both sides equal \(-\frac{3}{4}\), confirming \(x = -3\) is a valid solution.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Factoring Polynomials
Factoring polynomials is a crucial step in simplifying complex equations. When you encounter a polynomial such as \(x^2 - 1\), it can often be rewritten to make solving the equation easier.
In this case, \(x^2 - 1\) can be factored into \((x-1)(x+1)\).
In this case, \(x^2 - 1\) can be factored into \((x-1)(x+1)\).
- Factoring helps in identifying common roots and expressing the polynomial in a more manageable form.
- This technique simplifies operations like addition, subtraction, or finding common denominators of algebraic fractions.
Common Denominator
Finding a common denominator is a pivotal step in solving equations that involve fractions. In the given equation, \(\frac{2 x}{x^{2}-1} = \frac{2}{x+1} - \frac{1}{x-1}\), each side has different denominators initially.
To solve, you need to convert these into a common denominator to manage the fractions effectively.
To solve, you need to convert these into a common denominator to manage the fractions effectively.
- The common denominator here is \((x-1)(x+1)\), which simplifies the equation handling.
- Doing so ensures that each fraction can be combined or compared easily.
Cross-Multiplication
Once the fractions have a common denominator on both sides of an equation, you can effectively clear these denominators using cross-multiplication. Here, it involves setting the numerators equal since the denominators are already the same.
This method transforms \(\frac{2x}{(x-1)(x+1)} = \frac{x - 3}{(x-1)(x+1)}\) into the simpler form of equation, \(2x = x - 3\).
This method transforms \(\frac{2x}{(x-1)(x+1)} = \frac{x - 3}{(x-1)(x+1)}\) into the simpler form of equation, \(2x = x - 3\).
- This step is pivotal because it converts a complex fraction into a straightforward linear equation.
- With the numerators isolated, solving becomes a matter of basic algebra, enhancing clarity and focus on solving for the variable.
Verification of Solutions
After calculating potential solutions, verifying them is key to ensuring accuracy. When \(x = -3\) was found as a solution, it was necessary to substitute it back into the original equation to confirm its validity.
Here's how:
Here's how:
- Substituting \(x = -3\) into both sides yielded \(-\frac{3}{4}\) as the result, confirming the solution.
- This verification step checks for any errors in computation or extraneous solutions that may not satisfy the original equation.