Determining the Equation of the Quadratic Function

Oct 13, 2025 by wbrum.org 39 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 analyze a table of pairs of values for a quadratic function and determine the equation of the function.

The Table of Pairs

The table below shows pairs of values for a quadratic function.

$x$	$y$
-3	-3
-2	0
-1	1
0	0
1	-3
2	-8

Determining the Equation of the Quadratic Function

To determine the equation of the quadratic function, we need to find the values of $a$ , $b$ , and $c$ . We can do this by using the given pairs of values and substituting them into the general form of the quadratic function.

Let's start by substituting the first pair of values, (-3, -3), into the general form of the quadratic function:

f(-3) = a(-3)^2 + b(-3) + c

-3 = 9a - 3b + c

Now, let's substitute the second pair of values, (-2, 0), into the general form of the quadratic function:

f(-2) = a(-2)^2 + b(-2) + c

0 = 4a - 2b + c

We now have two equations with three unknowns. We can solve this system of equations by using substitution or elimination. Let's use substitution.

Solving the System of Equations

We can solve the first equation for $c$ :

c = -3 - 9a + 3b

Now, substitute this expression for $c$ into the second equation:

0 = 4a - 2b + (-3 - 9a + 3b)

0 = -5a - b - 3

Now, we have a new equation with two unknowns. We can solve this equation for $b$ :

b = -5a - 3

Now, substitute this expression for $b$ into the first equation:

-3 = 9a - 3(-5a - 3) + (-3 - 9a + 3(-5a - 3))

-3 = 9a + 15a + 9 - 3 - 9a - 3 + 15a + 9

-3 = 21a + 12

Now, we can solve this equation for $a$ :

a = -\frac{15}{21}

a = -\frac{5}{7}

Now that we have the value of $a$ , we can find the value of $b$ :

b = -5\left(-\frac{5}{7}\right) - 3

b = \frac{25}{7} - 3

b = \frac{25 - 21}{7}

b = \frac{4}{7}

Now that we have the values of $a$ and $b$ , we can find the value of $c$ :

c = -3 - 9\left(-\frac{5}{7}\right) + 3\left(\frac{4}{7}\right)

c = -3 + \frac{45}{7} + \frac{12}{7}

c = -3 + \frac{57}{7}

c = \frac{-21 + 57}{7}

c = \frac{36}{7}

The Equation of the Quadratic Function

Now that we have the values of $a$ , $b$ , and $c$ , we can write the equation of the quadratic function:

f(x) = -\frac{5}{7}x^2 + \frac{4}{7}x + \frac{36}{7}

Conclusion

In this article, we analyzed a table of pairs of values for a quadratic function and determined the equation of the function. We used the given pairs of values and substituted them into the general form of the quadratic function to find the values of $a$ , $b$ , and $c$ . We then solved the system of equations to find the values of $a$ , $b$ , and $c$ . Finally, we wrote the equation of the quadratic function using the values of $a$ , $b$ , and $c$ .

References

[1] "Quadratic Functions" by Math Open Reference
[2] "Quadratic Equations" by Khan Academy

Introduction

In our previous article, we analyzed a table of pairs of values for a quadratic function and determined the equation of the function. In this article, we will answer some frequently asked questions about quadratic function pairs and provide additional information to help you better understand this topic.

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: How do I determine the equation of a quadratic function from a table of pairs of values?

A: To determine the equation of a quadratic function from a table of pairs of values, you need to substitute the given pairs of values into the general form of the quadratic function and solve the resulting system of equations.

Q: What is the difference between a quadratic function and a linear function?

A: A quadratic function is a polynomial function of degree two, while a linear function is a polynomial function of degree one. The general form of a linear function is $f(x) = mx + b$ , where $m$ and $b$ are constants.

Q: Can I use a table of pairs of values to determine the equation of a linear function?

A: Yes, you can use a table of pairs of values to determine the equation of a linear function. However, you will only need to substitute the given pairs of values into the general form of the linear function and solve for the constants $m$ and $b$ .

Q: What is the significance of the coefficients $a$ , $b$ , and $c$ in a quadratic function?

A: The coefficients $a$ , $b$ , and $c$ in a quadratic function determine the shape and position of the graph of the function. The coefficient $a$ determines the direction and width of the parabola, while the coefficients $b$ and $c$ determine the position of the vertex of the parabola.

Q: Can I use a table of pairs of values to determine the equation of a cubic function?

A: No, you cannot use a table of pairs of values to determine the equation of a cubic function. A cubic function is a polynomial function of degree three, and it requires three pairs of values to determine the equation.

Q: What is the difference between a quadratic function and a polynomial function of degree two?

A: A quadratic function is a polynomial function of degree two that has a specific form, $f(x) = ax^2 + bx + c$ , where $a$ , $b$ , and $c$ are constants. A polynomial function of degree two is a more general term that refers to any function of the form $f(x) = ax^2 + bx + c$ , regardless of the values of $a$ , $b$ , and $c$ .

Q: Can I use a table of pairs of values to determine the equation of a polynomial function of degree two?

A: Yes, you can use a table of pairs of values to determine the equation of a polynomial function of degree two. However, you will need to substitute the given pairs of values into the general form of the polynomial function and solve for the constants $a$ , $b$ , and $c$ .

Conclusion

In this article, we answered some frequently asked questions about quadratic function pairs and provided additional information to help you better understand this topic. We hope this article has been helpful in clarifying any confusion you may have had about quadratic function pairs.

References

[1] "Quadratic Functions" by Math Open Reference
[2] "Quadratic Equations" by Khan Academy
[3] "Polynomial Functions" by Wolfram MathWorld
[4] "Polynomial Equations" by Math Is Fun