Chapter 6: Problem 77
Multiply or divide as indicated. $$ \left(z^{2}-1\right) \cdot \frac{1}{1-z} $$
Short Answer
Expert verified
-z - 1
Step by step solution
01
Factorize the numerator
Observe the term \((z^2 - 1)\). This is a difference of squares which can be factorized as \(z^2 - 1 = (z - 1)(z + 1)\). Rewrite the expression using this factorization.
02
Write the expression with factored numerator
Substitute the factorized form into the expression: \((z-1)(z+1) \cdot \frac{1}{1 - z}\).
03
Simplify the denominator
Notice that \(1 - z\) can be written as \(-(z - 1)\). Substitute this into the expression: \( (z-1)(z+1) \cdot \frac{1}{-(z - 1)} \).
04
Simplify the expression
Cancel out the common terms \(z - 1\) in the numerator and the denominator: \( (z-1)(z+1) \cdot \frac{1}{-(z - 1)} = (z + 1) \cdot \frac{1}{-1} \).
05
Final simplification
Simplify \( (z + 1) \cdot \frac{1}{-1} = -(z + 1) \). The final expression is \ -z - 1 \.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
In algebra, the *difference of squares* is a very common concept. It refers to an expression that can be written in the form \( a^2 - b^2 \). This is a special factorization pattern because this difference can always be factored into two binomials. For example, the expression \( z^2 - 1 \) can be written as \( (z - 1)(z + 1) \).This pattern works because \( a^2 - b^2 \) always equals \((a - b)(a + b)\).This is a handy tool for simplifying algebraic expressions.
Factorization
*Factorization* is the process of breaking down an expression into its simplest parts (factors). Factorizing can involve numbers, variables, or a combination of both. With our example, the expression \( z^2 - 1 \) was factorized into \( (z - 1)(z + 1) \).This is crucial because simplifying expressions often starts with factorizing. When you see an expression you suspect can be factored, look for patterns like the difference of squares. Some tips:
- Look for common factors first.
- Check for special patterns (e.g., difference of squares, perfect square trinomials).
- Factor step-by-step and simplify as you go.
Simplifying Rational Expressions
*Simplifying rational expressions* involves reducing fractions where both the numerator and the denominator are polynomials. The main steps include:
- Factorizing both the numerator and the denominator.
- Canceling out common factors in the numerator and the denominator.
Algebraic Manipulation
*Algebraic manipulation* entails performing operations to rewrite expressions in a more desirable form. You may add, subtract, multiply, divide, or factorize terms in an expression. In this example, a couple of key manipulations include:
Keep these principles in mind, and you’ll find handling algebraic expressions more intuitive over time.
- Rewriting \(1 - z \) as \(-(z - 1) \), a useful step for simplification.
- Canceling common factors such as \(z - 1 \) in both the numerator and the denominator.
Keep these principles in mind, and you’ll find handling algebraic expressions more intuitive over time.