Chapter 6: Problem 55
Add or subtract as indicated. If possible, simplify your answer. See Examples I through 6. $$ \frac{3}{2 x+10}+\frac{8}{3 x+15} $$
Short Answer
Expert verified
\(\frac{25}{6(x+5)}\)
Step by step solution
01
Identify and simplify the denominators
The denominators in the expression are \(2x + 10\) and \(3x + 15\). Notice both can be factored. The first denominator can be rewritten as \(2(x + 5)\) and the second as \(3(x + 5)\). This helps in finding a common denominator.
02
Find the least common denominator (LCD)
To add these fractions, we need a common denominator. Since both denominators have the term \((x + 5)\), the least common denominator is \(2 \cdot 3 \cdot (x + 5) = 6(x + 5)\).
03
Rewrite fractions with the LCD
Convert each fraction to have the common denominator \(6(x + 5)\). Multiply the first fraction by \(3\) (to account for the \(3\) in the second denominator) and the second fraction by \(2\) (to account for the \(2\) in the first denominator):\[\frac{3 \cdot 3}{6(x+5)} + \frac{8 \cdot 2}{6(x+5)} = \frac{9}{6(x+5)} + \frac{16}{6(x+5)}\]
04
Add the fractions
Now that they have the same denominator, add the numerators:\[\frac{9 + 16}{6(x+5)} = \frac{25}{6(x+5)}\]
05
Simplify if possible
Check if the fraction can be simplified. In this case, \(\frac{25}{6(x + 5)}\) is already in its simplest form, as there are no common factors between 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.
Finding the Least Common Denominator
Adding fractions requires a shared base, called the least common denominator (LCD). This ensures the fractions can be combined properly. Here's how you find it:
- Factor each denominator. In our example, the denominators are \(2x + 10\) and \(3x + 15\). By factoring, we get \(2(x + 5)\) and \(3(x + 5)\).
- Determine the LCD by taking the highest power of each factor present in both denominators. Here, they share \((x + 5)\). To make the LCD, multiply the separate numbers \(2\) and \(3\) together, along with the common factor \((x + 5)\).
Simplifying Fractions
Simplifying fractions makes them easier to work with and often appears as a final task when performing operations with fractions. This step involves reducing the expression to its simplest form:
- Check both the numerator and the denominator for common factors.
- In our example \( \frac{25}{6(x+5)} \), we see the numerator is 25 and the denominator is \(6(x+5)\).
- Since 25 and 6 don't share any factors other than 1, and \(x + 5\) does not affect the numerical part directly, the fraction is already simplified.
Factoring Expressions
Factoring is breaking down a complicated expression into simpler, multipliable elements. It's a critical skill in algebra that aids in solving equations and simplifying expressions.
- Start by identifying common factors in a term. In our expressions \(2x + 10\) and \(3x + 15\), notice both terms have a common element \(x + 5\).
- Factor out these common terms: \(2x + 10\) becomes \(2(x + 5)\), and \(3x + 15\) becomes \(3(x + 5)\). This step helps identify shared components for further operations like finding the LCD.