Chapter 9: Problem 72
Simplify. $$ \frac{3}{x-2}-\frac{x+1}{x} $$
Short Answer
Expert verified
\[ \frac{-x^2 + 4x + 2}{x(x-2)} \]
Step by step solution
01
Find a Common Denominator
To subtract these fractions, they must have a common denominator. The denominators are \(x-2\) and \(x\). The common denominator will be \(x(x-2)\).
02
Adjust First Fraction
The first fraction is \(\frac{3}{x-2}\). To get a common denominator \(x(x-2)\), multiply the numerator and the denominator by \(x\). This gives: \frac{3 \cdot x}{(x-2) \cdot x} = \frac{3x}{x(x-2)}\.
03
Adjust Second Fraction
The second fraction is \frac{x+1}{x}\. To get a common denominator \(x(x-2)\), multiply the numerator and the denominator by \((x-2)\). This gives: \frac{(x+1)(x-2)}{x(x-2)}\.
04
Combine the Fractions
Now, we have: \[\frac{3x}{x(x-2)} - \frac{(x+1)(x-2)}{x(x-2)}\] Since the denominators are the same, subtract the numerators: \[\frac{3x - (x+1)(x-2)}{x(x-2)}\]
05
Expand and Simplify
Expand \( (x+1)(x-2) \): \[(x+1)(x-2) = x^2 - 2x + x - 2 = x^2 - x - 2\]Now, substitute this into the expression: \[\frac{3x - (x^2 - x - 2)}{x(x-2)}\] Combine like terms: \[3x - x^2 + x + 2 = -x^2 + 4x + 2\]Giving us the new numerator: \[\frac{-x^2 + 4x + 2}{x(x-2)}\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fraction Subtraction
Subtracting fractions can seem tricky, but it becomes easier with a step-by-step approach.
Fractions must have the same denominator before you can subtract them.
Once they share a common denominator, you can combine them easily. In our exercise, the fractions are \(\frac{3}{x-2}\) and \(\frac{x+1}{x}\).
At first, these fractions do not have a common denominator.
That's why we need the next core concept: common denominators.
Fractions must have the same denominator before you can subtract them.
Once they share a common denominator, you can combine them easily. In our exercise, the fractions are \(\frac{3}{x-2}\) and \(\frac{x+1}{x}\).
At first, these fractions do not have a common denominator.
That's why we need the next core concept: common denominators.
Common Denominators
A common denominator is essential to combine fractions.
The common denominator of two fractions is a multiple of their denominators. Here, the denominators are \((x-2)\) and \((x)\). The least common multiple (LCM) of these is \((x(x-2))\).
By adjusting each fraction to have this new common denominator, we can simplify the calculation:
1. For \(\frac{3}{x-2}\), multiply the numerator and denominator by \(x\), getting \(\frac{3x}{x(x-2)}\).
2. For \(\frac{x+1}{x}\), multiply the numerator and denominator by \((x-2)\), getting \(\frac{(x+1)(x-2)}{x(x-2)}\).
Now both fractions are ready to be subtracted.
The common denominator of two fractions is a multiple of their denominators. Here, the denominators are \((x-2)\) and \((x)\). The least common multiple (LCM) of these is \((x(x-2))\).
By adjusting each fraction to have this new common denominator, we can simplify the calculation:
1. For \(\frac{3}{x-2}\), multiply the numerator and denominator by \(x\), getting \(\frac{3x}{x(x-2)}\).
2. For \(\frac{x+1}{x}\), multiply the numerator and denominator by \((x-2)\), getting \(\frac{(x+1)(x-2)}{x(x-2)}\).
Now both fractions are ready to be subtracted.
Expanding Expressions
Expressions often need expanding to simplify them further.
In our case, after adjusting the fractions to a common denominator, we need to subtract the numerators.
That means we need to handle \((x+1)(x-2))\):
- First, expand \((x+1)(x-2)\) to get \(x^2 - x - 2\).
- Next, combine like terms in the final step: Subtract the expanded expression from the first numerator: 3x - (x^2 - x - 2).
Simplifying this, we get \(-x^2 + 4x + 2\).
The last step is to place this new numerator over the original common denominator: \(\frac{-x^2 + 4x + 2}{x(x-2)}\).
Here's the fully simplified expression!
In our case, after adjusting the fractions to a common denominator, we need to subtract the numerators.
That means we need to handle \((x+1)(x-2))\):
- First, expand \((x+1)(x-2)\) to get \(x^2 - x - 2\).
- Next, combine like terms in the final step: Subtract the expanded expression from the first numerator: 3x - (x^2 - x - 2).
Simplifying this, we get \(-x^2 + 4x + 2\).
The last step is to place this new numerator over the original common denominator: \(\frac{-x^2 + 4x + 2}{x(x-2)}\).
Here's the fully simplified expression!