Chapter 1: Problem 30
Find the domain and range and sketch the graph of the function \(h(x)=\sqrt{4-x^{2}}\)
Short Answer
Expert verified
Domain: \([-2, 2]\), Range: \([0, 2]\). Sketch is a semicircle above x-axis.
Step by step solution
01
Determine the Domain
The domain of a function is the set of all possible input values (usually x-values) for which the function is defined. For the function \(h(x) = \sqrt{4-x^2}\), the expression inside the square root, \(4-x^2\), must be non-negative because we cannot take the square root of a negative number. Thus, we must solve: \(4-x^2 \geq 0\). This can be rewritten as \(x^2 \leq 4\), which implies \(-2 \leq x \leq 2\). Therefore, the domain of \(h(x)\) is \([-2, 2]\).
02
Determine the Range
The range of a function is the set of all possible output values (usually y-values). Since the square root function produces non-negative results, \(h(x) = \sqrt{4-x^2}\) gives outputs from \(0\) to the maximum value it can attain. At \(x = 0\), \(h(0) = \sqrt{4} = 2\), so the maximum output value is \(2\). Therefore, the range of the function is \([0, 2]\).
03
Plot Key Points
To sketch the graph, plot key points within the domain. At \(x=-2\), \(h(-2) = \sqrt{4 - (-2)^2} = \sqrt{0} = 0\). Similarly, \(h(2) = \sqrt{0} = 0\). At \(x=0\), \(h(0) = \sqrt{4} = 2\). This establishes the endpoints and the peak of the semicircle.
04
Sketch the Graph
The function \(h(x) = \sqrt{4-x^2}\) is a half-circle (semicircle) with a radius of 2 centered at the origin (0,0) but extended horizontally across the x-axis from \(-2\) to \(2\). Sketch a semicircle above the x-axis with diameter endpoints \((-2,0)\) and \((2,0)\), reaching its maximum height at \((0,2)\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Domain of a Function
The domain of a function refers to all the possible inputs, which are typically the x-values. For a function to make sense mathematically, it must only include inputs that keep the expression valid. In the case of the square root function, like the one in our example: \(h(x) = \sqrt{4-x^2}\), the expression under the square root must be non-negative. We cannot take the square root of a negative value and remain in the realm of real numbers.To find the domain here, set up the inequality:
- \(4 - x^2 \geq 0\)
- This simplifies to \(x^2 \leq 4\)
- Solving gives \(-2 \leq x \leq 2\)
Range of a Function
The range of a function encompasses all possible output values, often represented by y-values. For the function \(h(x) = \sqrt{4-x^2}\), since it's a square root function, outputs are restricted to non-negative numbers.The critical point of the range is determined by the maximum value inside the square root. Plug in different domain values to see how the output behaves:
- At \(x = 0\), \(h(0) = \sqrt{4} = 2\). Therefore, 2 is the maximum value the function reaches.
- At the ends \(x = -2\) and \(x = 2\), \(h(-2) = \sqrt{0} = 0\) and similarly for \(h(2) = 0\).
Square Root Function
The square root function can initially seem tricky, but it becomes predictable once you get to know it. It always produces non-negative results because you can't have the square root of a negative number in the set of real numbers. This function reflects a semi-circular nature when paired with a squared expression under the root, such as \(\sqrt{4-x^2}\).A few key characteristics of the square root:
- It is only defined for non-negative values, ensuring real number outputs.
- The output grows smaller as you move further from the center (or peak) of the range.
- It's often used in various mathematical applications such as calculating distances, physics problems, and probability.
Graph Sketching
Graph sketching is a visual representation of the function's behaviour over its domain. With the function \(h(x) = \sqrt{4-x^2}\), graphing can offer an intuitive insight into how the outputs change as inputs vary. This particular function forms a semi-circle shape, so let's see how the graph should look.Steps to sketch the graph:
- Identify the critical points: with the given function, essential points are \((-2, 0)\), \(0, 2\), and \(2, 0)\).
- Start sketching from these endpoints. The line between each point forms the curved boundary of the semi-circle.
- The highest point on the graph will be \( (0, 2) \) which forms the peak of your semi-circle.