Plotting the Graph on a Coordinate Plane

Oct 13, 2025 by wbrum.org 125 views

Introduction

In mathematics, a quadratic function is a polynomial function of degree two, which means the highest power of the variable is two. The general form of a quadratic function is $f(x) = ax^2 + bx + c$ , where $a$ , $b$ , and $c$ are constants. In this article, we will focus on plotting a quadratic function of the form $f(x) = -\frac{1}{2} x^2$ on a specific domain.

Understanding the Domain

The domain of a function is the set of all possible input values for which the function is defined. In this case, the domain is given as $\{-2, 0, 2, 4\}$ . This means we need to find the corresponding output values for each of these input values.

Finding the Output Values

To find the output values, we need to substitute each input value into the function $f(x) = -\frac{1}{2} x^2$ and evaluate the expression.

Substituting $x = -2$

$f(-2) = -\frac{1}{2} (-2)^2$ $f(-2) = -\frac{1}{2} (4)$ $f(-2) = -2$

Substituting $x = 0$

$f(0) = -\frac{1}{2} (0)^2$ $f(0) = -\frac{1}{2} (0)$ $f(0) = 0$

Substituting $x = 2$

$f(2) = -\frac{1}{2} (2)^2$ $f(2) = -\frac{1}{2} (4)$ $f(2) = -2$

Substituting $x = 4$

$f(4) = -\frac{1}{2} (4)^2$ $f(4) = -\frac{1}{2} (16)$ $f(4) = -8$

Plotting the Graph

Now that we have found the output values for each input value, we can plot the graph of the function. The graph will be a parabola that opens downwards, since the coefficient of the $x^2$ term is negative.

Input Value	Output Value
-2	-2
0	0
2	-2
4	-8

Plotting the Graph on a Coordinate Plane

To plot the graph on a coordinate plane, we need to use the input values as the x-coordinates and the output values as the y-coordinates.

x	y
-2	-2
0	0
2	-2
4	-8

Plotting the Graph

To plot the graph, we need to draw a parabola that passes through the points (-2, -2), (0, 0), (2, -2), and (4, -8).

Conclusion

In this article, we have learned how to plot a quadratic function of the form $f(x) = -\frac{1}{2} x^2$ on a specific domain. We have found the output values for each input value and plotted the graph on a coordinate plane. The graph is a parabola that opens downwards, since the coefficient of the $x^2$ term is negative.

Tips and Variations

To plot a quadratic function with a positive coefficient of the $x^2$ term, simply change the sign of the coefficient.
To plot a quadratic function with a different domain, simply change the input values.
To plot a quadratic function with a different function, simply change the function.

Common Mistakes

Failing to find the output values for each input value.
Failing to plot the graph on a coordinate plane.
Failing to draw a parabola that passes through the points.

Real-World Applications

Plotting a quadratic function can be used to model real-world situations, such as the trajectory of a projectile or the growth of a population.
Plotting a quadratic function can be used to find the maximum or minimum value of a function.

References

[1] "Quadratic Functions" by Math Open Reference.
[2] "Plotting Graphs" by Math Is Fun.
Quadratic Function Q&A ==========================

Frequently Asked Questions

Q: What is a quadratic function?

A: A quadratic function is a polynomial function of degree two, which means the highest power of the variable is two. The general form of a quadratic function is $f(x) = ax^2 + bx + c$ , where $a$ , $b$ , and $c$ are constants.

Q: What is the domain of a quadratic function?

A: The domain of a quadratic function is the set of all possible input values for which the function is defined. In other words, it is the set of all possible values of $x$ for which the function is defined.

Q: How do I find the output values of a quadratic function?

A: To find the output values of a quadratic function, you need to substitute each input value into the function and evaluate the expression. For example, if the function is $f(x) = -\frac{1}{2} x^2$ , you would substitute each input value into the function and evaluate the expression.

Q: How do I plot a quadratic function on a coordinate plane?

A: To plot a quadratic function on a coordinate plane, you need to use the input values as the x-coordinates and the output values as the y-coordinates. Then, you need to draw a parabola that passes through the points.

Q: What is the graph of a quadratic function?

A: The graph of a quadratic function is a parabola that opens upwards or downwards, depending on the sign of the coefficient of the $x^2$ term.

Q: How do I determine the direction of the parabola?

A: To determine the direction of the parabola, you need to look at the sign of the coefficient of the $x^2$ term. If the coefficient is positive, the parabola opens upwards. If the coefficient is negative, the parabola opens downwards.

Q: Can I plot a quadratic function with a different domain?

A: Yes, you can plot a quadratic function with a different domain. Simply change the input values and find the corresponding output values.

Q: Can I plot a quadratic function with a different function?

A: Yes, you can plot a quadratic function with a different function. Simply change the function and find the corresponding output values.

Q: What are some real-world applications of quadratic functions?

A: Quadratic functions have many real-world applications, such as modeling the trajectory of a projectile, the growth of a population, and the motion of an object under the influence of gravity.

Q: How do I find the maximum or minimum value of a quadratic function?

A: To find the maximum or minimum value of a quadratic function, you need to find the vertex of the parabola. The vertex is the point on the parabola where the function reaches its maximum or minimum value.

Q: How do I find the vertex of a quadratic function?

A: To find the vertex of a quadratic function, you need to use the formula $x = -\frac{b}{2a}$ , where $a$ and $b$ are the coefficients of the $x^2$ and $x$ terms, respectively.

Q: What is the significance of the vertex of a quadratic function?

A: The vertex of a quadratic function is the point on the parabola where the function reaches its maximum or minimum value. It is an important concept in mathematics and has many real-world applications.

Q: Can I use a calculator to plot a quadratic function?

A: Yes, you can use a calculator to plot a quadratic function. Simply enter the function and the domain, and the calculator will plot the graph for you.

Q: What are some common mistakes to avoid when plotting a quadratic function?

A: Some common mistakes to avoid when plotting a quadratic function include failing to find the output values for each input value, failing to plot the graph on a coordinate plane, and failing to draw a parabola that passes through the points.

Q: How do I check my work when plotting a quadratic function?

A: To check your work when plotting a quadratic function, you need to verify that the graph passes through the points and that the parabola opens in the correct direction.