Chapter 5: Problem 21
Write down the reciprocal of the following: (a) \(\frac{1}{3}+\frac{1}{2}\) (b) \(\frac{x+y}{13}\) (c) \(\frac{2 R+1}{R-1}\) (d) \(4 !\)
Short Answer
Expert verified
(a) \( \frac{6}{5} \), (b) \( \frac{13}{x+y} \), (c) \( \frac{R-1}{2R+1} \), (d) \( \frac{1}{24} \)
Step by step solution
01
Calculate the sum of fractions
For part (a), add the fractions \( \frac{1}{3} \) and \( \frac{1}{2} \) by finding a common denominator: \( \frac{1}{3} + \frac{1}{2} = \frac{2}{6} + \frac{3}{6} = \frac{5}{6} \). The sum is \( \frac{5}{6} \).
02
Find the reciprocal of the sum (a)
The reciprocal of a fraction is achieved by flipping its numerator and denominator. Thus, the reciprocal of \( \frac{5}{6} \) is \( \frac{6}{5} \).
03
Determine the reciprocal of expression (b)
The expression \( \frac{x+y}{13} \) has a reciprocal found by flipping the fraction: \( \frac{13}{x+y} \).
04
Calculate the reciprocal of expression (c)
The reciprocal of \( \frac{2R+1}{R-1} \) is found similarly by flipping the fraction: \( \frac{R-1}{2R+1} \).
05
Evaluate factorial expression for (d)
Calculate \( 4! = 4 \times 3 \times 2 \times 1 = 24 \).
06
Find factorial reciprocal (d)
The reciprocal of \( 4! \) is \( \frac{1}{24} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Fraction Addition
Adding fractions is a foundational skill in mathematics. To combine fractions, you need to have a common denominator. This denominator is a shared multiple of the individual denominators. For instance, to add \(\frac{1}{3}\) and \(\frac{1}{2}\), the common denominator is 6. Think of it as a small party where each fraction must bring the same treat. Here, \(\frac{1}{3}\) becomes \(\frac{2}{6}\) and \(\frac{1}{2}\) converts to \(\frac{3}{6}\). Now they are speaking the same language! So they add up to \(\frac{5}{6}\).
- Ensure that denominators are the same before adding fractions.
- Convert each fraction to equivalent fractions with a common denominator.
- Combine the numerators once the denominators are equal.
Reciprocal Calculation
The reciprocal of a fraction is quite simply its flipped version, where the numerator becomes the denominator and vice versa.
For any fraction \(\frac{a}{b}\), the reciprocal is \(\frac{b}{a}\). It's like a fun switcheroo! Here’s how you can find the reciprocal:
For any fraction \(\frac{a}{b}\), the reciprocal is \(\frac{b}{a}\). It's like a fun switcheroo! Here’s how you can find the reciprocal:
- Identify the numerator and denominator.
- Flip them to form the reciprocal.
- For example, the reciprocal of \(\frac{5}{6}\) is \(\frac{6}{5}\).
Factorial Reciprocal
Factorials are a way to describe a number multiplied by each whole number less than itself, often represented by an exclamation mark. It's a major player in permutations and combinations. For example, \(4!\) means \(4\times3\times2\times1 = 24\). Once you have the number from a factorial, its reciprocal is just \(\frac{1}{\text{factorial}}\).
For instance, the reciprocal of \(4!\) is \(\frac{1}{24}\). Here’s how it works:
For instance, the reciprocal of \(4!\) is \(\frac{1}{24}\). Here’s how it works:
- Calculate the factorial value.
- Simplify \(\frac{1}{\text{factorial value}}\).
Common Denominator
Finding a common denominator is crucial when adding or comparing fractions. It ensures that all fractions are on equal footing, much like making sure everyone speaks the same language at a meeting.
The lowest common denominator (LCD) is the smallest number that all denominators can divide into cleanly.
Here is how to do it:
The lowest common denominator (LCD) is the smallest number that all denominators can divide into cleanly.
Here is how to do it:
- List some multiples of each denominator you’re working with.
- Identify the smallest multiple that appears in each list- that’s your common denominator!
- Convert each fraction to an equivalent fraction with the LCD as the new denominator.