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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 45

Determine whether each relation defines y as a function of x. Give the domain and range. y=√(4x+1)

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Identify the given relation: \(y = \sqrt{4x + 1}\). This means \(y\) is defined as the square root of the expression \(4x + 1\).
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: \(4x + 1 \geq 0\).
Solve the inequality \(4x + 1 \geq 0\) to find the domain. Subtract 1 from both sides: \(4x \geq -1\), then divide both sides by 4: \(x \geq -\frac{1}{4}\).
Check if the relation defines \(y\) as a function of \(x\). Since for each \(x\) in the domain there is exactly one non-negative value of \(y\) (the principal square root), this relation does define \(y\) as a function of \(x\).
Determine the range by considering the possible values of \(y\). Since \(y = \sqrt{4x + 1}\) and the square root function outputs only non-negative values, the smallest value of \(y\) is 0 (when \(x = -\frac{1}{4}\)), and \(y\) increases without bound as \(x\) increases. So, the range is \(y \geq 0\).

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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 when graphed.
추천 영상:
5:57
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:
3:51
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 = √(4x + 1), since square roots produce non-negative results, the range includes all y-values greater than or equal to zero.
추천 영상:
4:22
Domain & Range of Transformed Functions