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Ch. R - Algebra Review
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161, 9780135440780, 9780136881117, 9780135440827, 9780135924891Non è quello che usi tu?Cambia libro di testo
Capitolo 1, Problema 39

Determine whether each relation defines y as a function of x. Give the domain and range. See Example 5. y = √(4x + 1)

Guida verificata passo dopo passo
1
Step 1: Understand the given relation. The equation is \(y = \sqrt{4x + 1}\). This means \(y\) is defined as the square root of the expression \(4x + 1\).
Step 2: Determine if \(y\) is a function of \(x\). For each value of \(x\), check if there is exactly one corresponding value of \(y\). Since the square root function outputs only the non-negative root, for each \(x\) that makes \(4x + 1\) non-negative, there is exactly one \(y\). Therefore, \(y\) is a function of \(x\).
Step 3: Find the domain of the function. The expression inside the square root, \(4x + 1\), must be greater than or equal to zero to keep \(y\) real. Set up the inequality: \(4x + 1 \geq 0\).
Step 4: Solve the inequality for \(x\). Subtract 1 from both sides: \(4x \geq -1\), then divide both sides by 4: \(x \geq -\frac{1}{4}\). So, the domain is all real numbers \(x\) such that \(x \geq -\frac{1}{4}\).
Step 5: Determine the range of the function. Since \(y = \sqrt{4x + 1}\) and the square root function outputs values greater than or equal to zero, the smallest value of \(y\) is 0 (when \(x = -\frac{1}{4}\)). As \(x\) increases, \(y\) increases without bound. Therefore, the range is \(y \geq 0\).

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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 if for every x-value there is only one y-value. If multiple y-values exist for a single x, the relation is not a function.
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Domain of a Function

The domain is the set of all possible input values (x-values) for which the function is defined. For expressions involving square roots, the radicand must be non-negative to keep the output real, so the domain is restricted accordingly.
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Range of a Function

The range is the set of all possible output values (y-values) the function can take. For a square root function, the output is always non-negative since the square root of a non-negative number is non-negative, which helps determine the range.
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