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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 36a

Find f+gf+g, fgf-g, fgfg, and fg\(\frac{f}{g}\). Determine the domain for each function.
f(x)=6x2x1f\(\left\)(x\(\right\))=6x^2-x-1, g(x)=x1g\(\left\)(x\(\right\))=x-1

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Step 1: Understand the problem. You are tasked with finding the domain of the functions f(x) = 6x^2 - x - 1 and g(x) = x - 1, as well as the domain of their combinations: f + g, f - g, fg, and f/g. The domain of a function is the set of all x-values for which the function is defined.
Step 2: Analyze the domain of f(x). Since f(x) = 6x^2 - x - 1 is a polynomial, it is defined for all real numbers. Therefore, the domain of f(x) is all real numbers.
Step 3: Analyze the domain of g(x). The function g(x) = x - 1 is also a polynomial, so it is defined for all real numbers. Thus, the domain of g(x) is all real numbers.
Step 4: Determine the domain of f + g, f - g, and fg. Since these operations involve adding, subtracting, or multiplying two polynomials, the resulting functions are also polynomials. Therefore, the domain of f + g, f - g, and fg is all real numbers.
Step 5: Determine the domain of f/g. Division by zero is undefined, so we must exclude any x-values that make g(x) = 0. Solve g(x) = x - 1 = 0, which gives x = 1. Therefore, the domain of f/g is all real numbers except x = 1.

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주요 개념

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

Function Operations

Function operations involve combining two or more functions through addition, subtraction, multiplication, or division. For example, if f(x) and g(x) are two functions, their sum is defined as (f + g)(x) = f(x) + g(x). Understanding these operations is crucial for manipulating and analyzing functions in algebra.
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Multiplying & Dividing Functions

Domain of a Function

The domain of a function is the set of all possible input values (x-values) for which the function is defined. For polynomial functions, like f(x) = 6x² - x - 1, the domain is all real numbers. However, for rational functions, such as g(x) = x - 1, the domain must exclude values that make the denominator zero.
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Domain Restrictions of Composed Functions

Rational Functions

Rational functions are ratios of two polynomials, expressed as f(x) = P(x)/Q(x), where P and Q are polynomials. The domain of a rational function is determined by identifying values that make the denominator zero, as these values are undefined. Understanding how to find the domain of rational functions is essential for solving problems involving function operations.
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Intro to Rational Functions