Chapter 7: Problem 36
Multiply or divide as indicated. $$ \frac{3 x+6}{20} \div \frac{4 x+8}{8} $$
Short Answer
Expert verified
The expression simplifies to \( \frac{3}{10} \).
Step by step solution
01
Interpret the Division
The problem asks us to divide two fractional expressions: \( \frac{3x+6}{20} \) by \( \frac{4x+8}{8} \). To divide fractions, we multiply the first fraction by the reciprocal of the second.
02
Find the Reciprocal
The reciprocal of \( \frac{4x+8}{8} \) is \( \frac{8}{4x+8} \). We will use this in the next step to facilitate the division.
03
Multiply by Reciprocal
Multiply \( \frac{3x+6}{20} \) by \( \frac{8}{4x+8} \). This can be set up as: \[ \frac{3x+6}{20} \times \frac{8}{4x+8} = \frac{(3x+6) \times 8}{20 \times (4x+8)} \]
04
Simplify Numerator
The numerator becomes: \( (3x+6) \times 8 = 24x + 48 \).
05
Simplify Denominator
The denominator can be simplified as: \( 20 \times (4x+8) = 80x + 160 \).
06
Combine and Simplify the Fraction
Now, the expression simplifies to: \[ \frac{24x + 48}{80x + 160} \]Factoring out common factors gives: \[ \frac{24(x + 2)}{80(x + 2)} \]This simplifies further by cancelling \( (x+2) \) in both numerator and denominator, resulting in \( \frac{24}{80} \).
07
Simplify the Reduced Fraction
Now simplify \( \frac{24}{80} \) by finding the greatest common divisor which is 8.Thus, dividing both terms, we get: \( \frac{24 \div 8}{80 \div 8} = \frac{3}{10} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Reciprocal
When we talk about dividing fractions, the concept of a *reciprocal* is essential. Simply put, a reciprocal is what you flip a fraction to. For example, the reciprocal of \( \frac{4}{5} \) is \( \frac{5}{4} \). When you multiply a number by its reciprocal, you get a product of 1. This rule is really useful in fraction division, because to divide by a fraction, you multiply by its reciprocal.
- Start by identifying the fraction you're dividing by.
- Flip the numerator and the denominator to find the reciprocal.
- Use this flipped fraction to multiply with the original fraction instead of dividing.
Common Factors
Understanding *common factors* helps us simplify fractions during calculations. Common factors are numbers that are a factor of two or more different numbers or expressions. When you simplify fractions, finding these shared factors can make your work easier.
- Look for numbers that divide both the numerator and denominator completely.
- Factor these out to reduce your fraction.
- This will often simplify into smaller, more manageable numbers.
Simplifying Fractions
Once you've handled the division and multiplication of fractions, the next task is *simplifying fractions*. The goal is to make the fraction as simple as possible. You do this by dividing both the numerator and the denominator by their greatest common divisor (GCD).
- Calculate or identify the greatest number that divides both the top and bottom seamlessly.
- Divide both parts of the fraction by this GCD.
- Your result should be the fraction in its lowest or simplest form.