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Ch. 2 - Functions and Graphs
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514당신이 사용하는 게 아니라요?교과서 변경
3장, 문제 42

Find f+gf+g, fgf-g, fgfg, and fg\(\frac{f}{g}\). Determine the domain for each function.
f(x)=61xf\(\left\)(x\(\right\))=6-\(\frac{1}{x}\), g(x)=1xg\(\left\)(x\(\right\))=\(\frac{1}{x}\)

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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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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

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.
추천 영상:
3:51
Domain Restrictions of Composed Functions

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.
추천 영상:
6:04
Intro to Rational Functions

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.
추천 영상:
7:24
Multiplying & Dividing Functions