Chapter 2: Problem 11
Graphing Functions Sketch a graph of the function by first making a table of values. $$g(x)=-(x+1)^{2}$$
Short Answer
Expert verified
The function graph is a downward-opening parabola with vertex at \((-1, 0)\).
Step by step solution
01
Understand the Function
The function given is \( g(x) = -(x + 1)^2 \). This is a quadratic function, which means its graph will be a parabola. Since the coefficient of \( x^2 \) is negative, the parabola will open downward.
02
Determine the Vertex
The function is in the form \( g(x) = -(x - h)^2 + k \). Here, \( h = -1 \) and \( k = 0 \). Thus, the vertex of the parabola is at \((-1, 0)\).
03
Create a Table of Values
Select some values of \( x \) to substitute into \( g(x) \) and calculate corresponding \( g(x) \) values:- For \( x = -3 \), \( g(-3) = -((-3 + 1)^2) = -(4) = -4 \).- For \( x = -2 \), \( g(-2) = -((-2 + 1)^2) = -(1) = -1 \).- For \( x = -1 \), \( g(-1) = -((-1 + 1)^2) = 0 \).- For \( x = 0 \), \( g(0) = -(0 + 1)^2 = -1 \).- For \( x = 1 \), \( g(1) = -(1 + 1)^2 = -4 \).This table helps visualize key points on the graph.
04
Plot the Points on a Graph
Using the values obtained in the table, plot the points:- \(( -3, -4 )\)- \(( -2, -1 )\)- \(( -1, 0 )\)- \(( 0, -1 )\)- \(( 1, -4 )\)Make sure the graph is a smooth curve passing through these points.
05
Sketch the Parabola
Draw a smooth curve through the plotted points, ensuring the vertex is at \(-1, 0\), and the parabola opens downward. This represents the function \( g(x) = -(x + 1)^2 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Parabola
A parabola is the U-shaped curve that represents the graph of a quadratic function. Quadratic functions take the form of \[ f(x) = ax^2 + bx + c \]. In this particular exercise, the function is \( g(x) = -(x + 1)^2 \). When you look at this function, it's clear that it doesn't have the standard quadratic form because it's expressed in the vertex form: \( g(x) = a(x - h)^2 + k \).
The most important part to recognize about the parabolas is the direction they open. You determine this from the leading coefficient \( a \):
The most important part to recognize about the parabolas is the direction they open. You determine this from the leading coefficient \( a \):
- If \( a > 0 \), the parabola opens upward, forming a smile shape.
- If \( a < 0 \), like in our example with \( g(x) = -(x +1)^2 \), the parabola opens downward.
Vertex
The vertex of a parabola is essentially its peak or valley. It is one of the fundamental characteristics of quadratic functions and gives you a lot of information about the graph.
In the vertex form of a quadratic function, \( y = a(x - h)^2 + k \), the vertex is located at \( (h, k) \). In our function \( g(x) = -(x + 1)^2 \), you'll notice it can be rewritten to \(-((x) - (-1))^2 + 0 \), identifying the vertex at \((-1, 0)\).
Why is the vertex important?
In the vertex form of a quadratic function, \( y = a(x - h)^2 + k \), the vertex is located at \( (h, k) \). In our function \( g(x) = -(x + 1)^2 \), you'll notice it can be rewritten to \(-((x) - (-1))^2 + 0 \), identifying the vertex at \((-1, 0)\).
Why is the vertex important?
- It tells you the highest or lowest point on the graph. For \( g(x) \), since the parabola opens downward, the vertex is the highest point.
- The vertex also indicates the line of symmetry of the parabola, which means both sides of the curve are mirror images of each other about a vertical line passing through the vertex.
Table of Values
Creating a table of values is an effective way to plot the graph of a function, especially when graphing a quadratic function like a parabola.One of the advantages of using a table of values is that it helps pinpoint precise locations on the graph to ensure accuracy.
To create the table of values for \( g(x) = -(x + 1)^2 \),
To create the table of values for \( g(x) = -(x + 1)^2 \),
- Start by selecting some values for \( x \). In this case, \( x = -3, -2, -1, 0, 1 \) were chosen.
- Next, plug each of these \( x \) values into the function to get the corresponding \( g(x) \) or \( y \) values.
- These calculations show the outcome of the function at specific points, resulting in pairs of coordinates like \( (-3, -4) \), \( (-2, -1) \), \( (-1, 0) \), \( (0, -1) \), and \( (1, -4) \).