Chapter 2: Problem 16
Graph each function. $$y=-\frac{1}{3} x^{2}$$
Short Answer
Expert verified
The graph is a downward-opening parabola with vertex at (0,0) and additional points at (-3,-3) and (3,-3).
Step by step solution
01
- Identify the basic form of the quadratic function
The given function is a quadratic function of the form \(y = ax^2\). In this case, \(a = -\frac{1}{3}\).
02
- Determine the direction of the parabola
Since \(a = -\frac{1}{3}\) is negative, the parabola opens downward.
03
- Find the vertex of the parabola
For a function in the form \(y = ax^2\), the vertex is at the origin, \( (0,0) \).
04
- Plot the vertex
Plot the point (0,0) on the coordinate plane.
05
- Choose additional points to plot the parabola
Select x-values to substitute into the function and find corresponding y-values. For example, \( x = -3 \) and \( x = 3 \).
06
- Calculate and plot additional points
For \( x = -3\): \(-\frac{1}{3}(-3)^2 = -\frac{1}{3} \cdot 9 = -3\). So, the point is (-3,-3). For \( x = 3\): \(-\frac{1}{3}(3)^2 = -\frac{1}{3} \cdot 9 = -3\). So, the point is (3,-3). Plot these points.
07
- Sketch the parabola
Using the points (0,0), (-3,-3), and (3,-3), draw a smooth curve to form the downward-opening parabola.
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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 function that can be written in the standard form \(y = ax^2 + bx + c\), where \(a\), \(b\), and \(c\) are constants, and \(a eq 0\). The graph of a quadratic function is always a parabola. In the equation provided in the exercise, the function is given as \(y = - \frac{1}{3} x^2 \).
- The term \(a\) determines the direction and the width of the parabola.
- Since \(a = - \frac{1}{3}\) in the given function, the parabola opens downward (because \(a\) is negative).
- The smaller the absolute value of \(a\), the wider the parabola will be. Here \(a = - \frac{1}{3}\), making the parabola relatively wide.
Parabola
A parabola is the U-shaped graph formed by plotting a quadratic function. Its key features include the direction it opens, which is determined by the sign of \(a\) in the quadratic function.The general characteristics of a parabola are:
- If \(a > 0\), it opens upwards, resembling a 'smiling' shape.
- If \(a < 0\), it opens downwards, resembling a 'frowning' shape.
Vertex
The vertex of a parabola is its highest or lowest point, depending on the direction the parabola opens. For the function \(y = ax^2\), the vertex is always at the origin, which is (0,0).
Here, the vertex is also (0,0). To find and plot the vertex:
Here, the vertex is also (0,0). To find and plot the vertex:
- Identify the value of \(a\) in the function.
- If the equation is in the form \(y = ax^2\), like in this example, the vertex is at (0,0).