Chapter 7: Problem 74
Simplify each complex fraction. $$ \frac{1}{\frac{b}{a}-\frac{a}{b}} $$
Short Answer
Expert verified
The simplified expression is \( \frac{ab}{(b-a)(b+a)} \).
Step by step solution
01
Identify the expression
The given complex fraction is \( \frac{1}{\frac{b}{a} - \frac{a}{b}} \). We need to simplify this expression.
02
Find a common denominator for the fractions in the denominator
The fractions in the denominator are \( \frac{b}{a} \) and \( \frac{a}{b} \). The common denominator for these fractions is \( ab \).
03
Rewrite each fraction with the common denominator
Rewrite \( \frac{b}{a} \) as \( \frac{b \cdot b}{a \cdot b} = \frac{b^2}{ab} \) and \( \frac{a}{b} \) as \( \frac{a \cdot a}{b \cdot a} = \frac{a^2}{ab} \).
04
Simplify the expression in the denominator
Now, subtract the fractions: \( \frac{b^2}{ab} - \frac{a^2}{ab} = \frac{b^2 - a^2}{ab} \).
05
Simplify \( \frac{1}{\frac{b^2 - a^2}{ab}} \)
The expression can be rewritten as \( \frac{ab}{b^2 - a^2} \), since dividing by a fraction is equivalent to multiplying by its reciprocal.
06
Factor the difference of squares in the denominator
The term \( b^2 - a^2 \) is a difference of squares, which can be factored as \( (b-a)(b+a) \).
07
Final simplified expression
Substitute the factored expression into \( \frac{ab}{b^2 - a^2} \) to get \( \frac{ab}{(b-a)(b+a)} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Common Denominator
When simplifying complex fractions, finding a common denominator is a crucial first step. It helps unify different fractions under a single denominator, making it easier to perform arithmetic operations. In our exercise, we encounter two fractions within the denominator: \( \frac{b}{a} \) and \( \frac{a}{b} \). To find a common denominator between these, we look for a number or expression that both denominators, \( a \) and \( b \), can divide into evenly.
- The common denominator for \( \frac{b}{a} \) and \( \frac{a}{b} \) is the product of both denominators: \( ab \).
- Rewriting fractions using a common denominator allows us to manipulate them as if they were whole numbers.
Difference of Squares
The expression \( b^2 - a^2 \) is recognized as a difference of squares, a concept you will encounter frequently in algebra. A difference of squares can always be factored using the identity: \[(x^2 - y^2 = (x-y)(x+y)\] This identity simplifies algebraic expressions and is particularly helpful when trying to simplify complex fractions. In the given exercise:
- We identify \( b^2 - a^2 \) within our fraction.
- This expression can be factored as \( (b-a)(b+a) \).
Fraction Simplification
Simplifying fractions to their simplest form includes reducing complex expressions into single, manageable fractions. The given problem involves a complex fraction \( \frac{1}{\frac{b^2 - a^2}{ab}} \).
- The first simplification involves recognizing that dividing by a fraction is the same as multiplying by its reciprocal. Thus, \( \frac{1}{\frac{b^2 - a^2}{ab}} \) becomes \( \frac{ab}{b^2 - a^2} \).
- Use the factored form \( \frac{ab}{(b-a)(b+a)} \) for simplification.