Chapter 2: Problem 13
Sketch the graph of the function by first making a table of values. $$h(x)=16-x^{2}$$
Short Answer
Expert verified
Plot points from table and connect to form a downward-opening parabola.
Step by step solution
01
Understand the Function
The given function is \( h(x) = 16 - x^2 \). This is a quadratic function which represents a parabola. The parabola opens downwards because the coefficient of \( x^2 \) is negative (-1). The vertex of this parabola is the highest point.
02
Find the Vertex
The standard form of the quadratic function is \( h(x) = ax^2 + bx + c \). In our function, \( a = -1 \), \( b = 0 \), and \( c = 16 \). The vertex \( x \)-coordinate is given by \( x = -\frac{b}{2a} \). Here, it simplifies to \( x = 0 \). Hence, the vertex is at \( (0, 16) \).
03
Create a Table of Values
Choose a set of \( x \)-values around the vertex, typically from \( -3 \) to \( 3 \) for simplicity. Calculate \( h(x) \) for these values:- When \( x = -3, h(x) = 16 - (-3)^2 = 7 \)- When \( x = -2, h(x) = 16 - (-2)^2 = 12 \)- When \( x = -1, h(x) = 16 - (-1)^2 = 15 \)- When \( x = 0, h(x) = 16 - 0^2 = 16 \)- When \( x = 1, h(x) = 16 - 1^2 = 15 \)- When \( x = 2, h(x) = 16 - 2^2 = 12 \)- When \( x = 3, h(x) = 16 - 3^2 = 7 \).
04
Sketch the Graph
Using the table of values, plot the points \((-3, 7)\), \((-2, 12)\), \((-1, 15)\), \((0, 16)\), \((1, 15)\), \((2, 12)\), and \((3, 7)\) on a coordinate plane. Connect these points with a smooth, downward-opening parabola. The symmetry about the \( y \)-axis should be evident.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Function
A quadratic function is a type of polynomial that can be expressed in the form \( f(x) = ax^2 + bx + c \). It's called a "quadratic" because it deals with squares, as the term \( x^2 \) is the highest power of the variable \( x \). This results in a U-shaped graph known as a parabola. In any quadratic function:
- \( a \) is the coefficient of \( x^2 \). It determines the direction the parabola opens. A positive \( a \) means it opens upwards, and a negative \( a \) makes it open downwards.
- \( b \) and \( c \) affect the position of the parabola on the graph.
- \( a = -1 \), causing the parabola to open downwards.
- \( b = 0 \), indicating the parabola is symmetric about the \( y \)-axis, or the line \( x = 0 \).
- \( c = 16 \), placing the highest point of the parabola at a height of 16 on the \( y \)-axis.
Vertex of Parabola
The vertex of a parabola is a crucial point that indicates the maximum or minimum value of the quadratic function. For a parabola that opens downwards, like in our example, the vertex is at the maximum point.
The vertex can be found using the formula for the \( x \)-coordinate: \( x = -\frac{b}{2a} \).
This point is where the parabola reaches its peak.
Knowing how to find the vertex is essential for graphing because it serves as a central point for the parabola's symmetry.
The vertex can be found using the formula for the \( x \)-coordinate: \( x = -\frac{b}{2a} \).
- For \( h(x) = 16 - x^2 \), we have \( a = -1 \) and \( b = 0 \).
- Substituting these into the formula gives \( x = -\frac{0}{-2} = 0 \).
- To find the \( y \)-coordinate, substitute \( x = 0 \) back into the function: \( h(0) = 16 - 0^2 = 16 \).
This point is where the parabola reaches its peak.
Knowing how to find the vertex is essential for graphing because it serves as a central point for the parabola's symmetry.
Table of Values
Creating a table of values is a helpful technique to visually understand how a quadratic function behaves over a range of \( x \)-values. By calculating \( h(x) \) for various \( x \)-values:
Once made, you can plot these points on a graph,
which creates the smooth, curved shape typical of a parabola.
This approach simplifies the graphing process and ensures accuracy.
- You can see how the function rises and falls, giving insight into its shape.
- Points of symmetry relative to the vertex become evident.
- Choose a range of \( x \) such as from \(-3\) to \(3\).
- Calculate \( h(x) \) for each value: \((-3, 7), (-2, 12), (-1, 15), (0, 16), (1, 15), (2, 12), (3, 7)\).
Once made, you can plot these points on a graph,
which creates the smooth, curved shape typical of a parabola.
This approach simplifies the graphing process and ensures accuracy.