Chapter 2: Problem 32
A function \(f\) is given. (a) Use a graphing calculator to draw the graph of \(f\) (b) Find the domain and range of \(f\) from the graph. $$f(x)=x^{2}+4$$
Short Answer
Expert verified
Domain: \((-\infty, \infty)\), Range: \([4, \infty)\).
Step by step solution
01
Understand the Function
The function given is \( f(x) = x^2 + 4 \). This is a quadratic function which is a simple parabola that opens upwards.
02
Graph the Function
Use a graphing calculator to plot the graph of the function \( f(x) = x^2 + 4 \). The vertex of the parabola is at (0, 4). The parabola opens upwards with its minimum point at the vertex.
03
Find the Domain
For a quadratic function of the form \( f(x) = x^2 + c \), the domain is all real numbers because you can input any real number for \( x \) and still get a valid output. Hence, the domain is \( (-fty, fty) \).
04
Find the Range
From the graph, observe that the minimum value of \( f(x) \) occurs at the vertex, which is \( c = 4 \). Since the parabola opens upwards, all values of \( f(x) \) are greater than or equal to 4. Thus, the range is \( [4, fty) \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
graphing functions
Graphing functions is a fundamental skill in mathematics that transforms equations into visual representations. For the given function, \( f(x) = x^2 + 4 \), graphing helps to see the shape and behavior of the function. This specific function is a quadratic, so it forms a parabola.
To graph any function effectively, especially quadratic ones like \( f(x) = ax^2 + bx + c \), follow these steps:
To graph any function effectively, especially quadratic ones like \( f(x) = ax^2 + bx + c \), follow these steps:
- Identify the Key Features: For quadratic functions, focus on the vertex, axis of symmetry, and direction of opening (up or down).
- Plot the Vertex: The vertex of \( f(x) = x^2 + 4 \) is at (0, 4). This is where the parabola reaches its minimum point.
- Determine the Direction: If the coefficient of \( x^2 \) is positive, the parabola opens upwards, as in our function.
- Sketch the Curve: Use a graphing calculator for a precise plot, but remember the basic shape and direction.
domain and range
Understanding the domain and range of a function is crucial for evaluating where the function operates and the outputs it can produce. The domain refers to all possible input values \( x \), while the range refers to all potential output values \( f(x) \). For the given quadratic function \( f(x) = x^2 + 4 \):
- Domain: Quadratic functions like this are defined for all real numbers. Thus, the domain of \( f(x) = x^2 + 4 \) is \( (-\infty, \infty) \), indicating that you can substitute any real number for \( x \). There are no restrictions like square roots or fractions.
- Range: Since the parabola opens upwards and its vertex is at \( y = 4 \), all output values \( f(x) \) will be 4 or greater. Therefore, the range is \( [4, \infty) \), highlighting that the minimum output the function can produce is 4, after which it increases infinitely.
parabolas
Parabolas are U-shaped graphs that represent quadratic functions. They play a notable role in mathematics due to their symmetrical properties and appearance in various natural phenomena. Our function \( f(x) = x^2 + 4 \) forms a basic parabola.
- Characteristics of Parabolas: They have a line of symmetry, which passes through the vertex. In \( f(x) = x^2 + 4 \), the line of symmetry is x=0 since the vertex is (0, 4).
- The Vertex: This point is crucial as it represents the minimum (or maximum) value of the function. For this function, the vertex is a minimum at (0, 4).
- Opening Direction: Parabolas can open upwards or downwards. If the \( x^2 \) term is positive, like in our function, the parabola opens upwards.
- Applications: Parabolas find application in physics, engineering, and optics, such as the paths of projectiles or light reflection in car headlights.