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Ch. 2 - Graphs and Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
3장, 문제 46

Determine whether each relation defines y as a function of x. Give the domain and range. y=√(7-2x)

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Identify the given relation: \(y = \sqrt{7 - 2x}\). This means \(y\) is defined as the square root of the expression \(7 - 2x\).
Determine the domain by finding all values of \(x\) for which the expression inside the square root is non-negative, since the square root of a negative number is not a real number. Set up the inequality: \(7 - 2x \geq 0\).
Solve the inequality for \(x\): Subtract 7 from both sides to get \(-2x \geq -7\), then divide both sides by \(-2\). Remember to reverse the inequality sign when dividing by a negative number, resulting in \(x \leq \frac{7}{2}\).
Check if the relation defines \(y\) as a function of \(x\): For each \(x\) in the domain, there is exactly one value of \(y\) because the square root function outputs only the non-negative root. Therefore, \(y\) is a function of \(x\).
Determine the range by considering the possible values of \(y\). Since \(y = \sqrt{7 - 2x}\) and the square root is always non-negative, the smallest value of \(y\) is 0 (when \(7 - 2x = 0\)), and the largest value occurs when \(7 - 2x\) is maximized (which is 7 when \(x = 0\)). So, the range is \(y \geq 0\) up to \(y \leq \sqrt{7}\).

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주요 개념

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

Definition of a Function

A function is a relation where each input x corresponds to exactly one output y. To determine if y is a function of x, check that for every x-value there is only one y-value. This ensures the relation passes the vertical line test if graphed.
추천 영상:
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Graphs of Common Functions

Domain of a Function

The domain is the set of all possible input values (x-values) for which the function is defined. For functions involving square roots, the expression inside the root must be non-negative to yield real outputs, restricting the domain accordingly.
추천 영상:
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Domain Restrictions of Composed Functions

Range of a Function

The range is the set of all possible output values (y-values) of the function. For y = √(7 - 2x), since the square root produces only non-negative values, the range consists of all y ≥ 0, adjusted by the domain restrictions.
추천 영상:
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Domain & Range of Transformed Functions