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Ch. 2 - Functions and Graphs
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Non è quello che usi tu?Cambia libro di testo
Capitolo 3, Problema 42

Find f+gf+g, f−gf-g, fgfg, and fg\(\frac{f}{g}\). Determine the domain for each function.
f(x)=6−1xf\(\left\)(x\(\right\))=6-\(\frac{1}{x}\), g(x)=1xg\(\left\)(x\(\right\))=\(\frac{1}{x}\)

Guida verificata passo dopo passo
1
To find \( (f+g)(x) \), add the functions: \( f(x) = 6 - \frac{1}{x} \) and \( g(x) = \frac{1}{x} \). Combine like terms: \( (f+g)(x) = 6 - \frac{1}{x} + \frac{1}{x} = 6 \). The domain of \( f+g \) is all real numbers except \( x = 0 \) because division by zero is undefined.
To find \( (f-g)(x) \), subtract the functions: \( f(x) = 6 - \frac{1}{x} \) and \( g(x) = \frac{1}{x} \). Combine like terms: \( (f-g)(x) = 6 - \frac{1}{x} - \frac{1}{x} = 6 - \frac{2}{x} \). The domain of \( f-g \) is all real numbers except \( x = 0 \).
To find \( (fg)(x) \), multiply the functions: \( f(x) = 6 - \frac{1}{x} \) and \( g(x) = \frac{1}{x} \). Distribute \( g(x) \) into \( f(x) \): \( (fg)(x) = (6 - \frac{1}{x}) \cdot \frac{1}{x} = \frac{6}{x} - \frac{1}{x^2} \). The domain of \( fg \) is all real numbers except \( x = 0 \).
To find \( \frac{f}{g}(x) \), divide the functions: \( f(x) = 6 - \frac{1}{x} \) and \( g(x) = \frac{1}{x} \). Perform the division: \( \frac{f}{g}(x) = \frac{6 - \frac{1}{x}}{\frac{1}{x}} = x(6 - \frac{1}{x}) = 6x - 1 \). The domain of \( \frac{f}{g} \) is all real numbers except \( x = 0 \).
For each function, ensure the domain excludes \( x = 0 \) because both \( f(x) \) and \( g(x) \) involve division by \( x \), which is undefined at \( x = 0 \).

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Concetti chiave

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Function Domain

The domain of a function refers to the set of all possible input values (x-values) for which the function is defined. For rational functions, like f(x) = 6 - 1/x and g(x) = 1/x, the domain excludes any values that make the denominator zero, as division by zero is undefined.
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Rational Functions

Rational functions are expressions formed by the ratio of two polynomials. They can exhibit unique behaviors, such as vertical asymptotes where the denominator equals zero. Understanding the structure of rational functions is crucial for determining their domains and identifying points of discontinuity.
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Operations on Functions

Operations on functions, such as addition, subtraction, multiplication, and division, involve combining two functions to create a new function. Each operation may affect the domain of the resulting function, particularly when division is involved, as it can introduce restrictions based on the original functions' domains.
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