Factored Form of a Quadratic Equation

Oct 13, 2025 by wbrum.org 10 views

Introduction

Quadratic equations are a fundamental concept in mathematics, and graphing them is an essential skill for students and professionals alike. In this article, we will explore how to graph a quadratic equation in factored form, using the given equation as an example.

What is a Quadratic Equation?

A quadratic equation is a polynomial equation of degree two, which means the highest power of the variable (usually x) is two. The general form of a quadratic equation is:

ax^2 + bx + c = 0

where a, b, and c are constants. Quadratic equations can be solved using various methods, including factoring, the quadratic formula, and graphing.

Factored Form of a Quadratic Equation

The factored form of a quadratic equation is a product of two binomials, each of which is a linear expression. The general form of a quadratic equation in factored form is:

y = a(x - r)(x - s)

where r and s are the roots of the equation, and a is a constant. The factored form is useful for graphing quadratic equations, as it allows us to identify the x-intercepts and the vertex of the parabola.

Graphing a Quadratic Equation in Factored Form

To graph a quadratic equation in factored form, we need to identify the x-intercepts and the vertex of the parabola. The x-intercepts are the values of x that make the equation equal to zero, and the vertex is the point on the parabola that is lowest or highest.

Step 1: Identify the X-Intercepts

To identify the x-intercepts, we need to set the equation equal to zero and solve for x. In the given equation, y = -\frac{1}{3}(x-4)(x+3), we can set y equal to zero and solve for x:

0 = -\frac{1}{3}(x-4)(x+3)

Multiplying both sides by -3, we get:

0 = (x-4)(x+3)

Expanding the right-hand side, we get:

0 = x^2 - x - 12

Factoring the quadratic expression, we get:

0 = (x - 4)(x + 3)

Setting each factor equal to zero, we get:

x - 4 = 0 or x + 3 = 0

Solving for x, we get:

x = 4 or x = -3

Therefore, the x-intercepts are x = 4 and x = -3.

Step 2: Identify the Vertex

The vertex of the parabola is the point on the parabola that is lowest or highest. To find the vertex, we need to find the x-coordinate of the vertex, which is the average of the x-intercepts. The x-coordinate of the vertex is:

x = \frac{4 + (-3)}{2} = \frac{1}{2}

To find the y-coordinate of the vertex, we need to plug the x-coordinate into the equation:

y = -\frac{1}{3}(\frac{1}{2} - 4)(\frac{1}{2} + 3)

Simplifying the expression, we get:

y = -\frac{1}{3}(-\frac{7}{2})(\frac{7}{2})

y = \frac{49}{12}

Therefore, the vertex is the point (\frac{1}{2}, \frac{49}{12}).

Step 3: Plot the X-Intercepts and the Vertex

To graph the quadratic equation, we need to plot the x-intercepts and the vertex on a coordinate plane. The x-intercepts are the points (4, 0) and (-3, 0), and the vertex is the point (\frac{1}{2}, \frac{49}{12}).

Step 4: Draw the Parabola

To draw the parabola, we need to connect the x-intercepts and the vertex with a smooth curve. The parabola opens downward, since the coefficient of the x^2 term is negative.

Conclusion

Graphing a quadratic equation in factored form is a useful skill for students and professionals alike. By identifying the x-intercepts and the vertex, we can graph the parabola and understand its behavior. In this article, we used the given equation as an example and walked through the steps to graph the quadratic equation.

Example Problems

Graph the quadratic equation y = 2(x - 2)(x + 1).
Graph the quadratic equation y = -\frac{1}{2}(x - 1)(x + 2).
Graph the quadratic equation y = x^2 - 4x - 3.

Solutions

To graph the quadratic equation y = 2(x - 2)(x + 1), we need to identify the x-intercepts and the vertex. The x-intercepts are x = 2 and x = -1, and the vertex is the point (0.5, -1.5).
To graph the quadratic equation y = -\frac{1}{2}(x - 1)(x + 2), we need to identify the x-intercepts and the vertex. The x-intercepts are x = 1 and x = -2, and the vertex is the point (-0.5, 0.5).
To graph the quadratic equation y = x^2 - 4x - 3, we need to identify the x-intercepts and the vertex. The x-intercepts are x = -1 and x = 3, and the vertex is the point (1, -4).

Final Thoughts

Introduction

In our previous article, we explored how to graph quadratic equations in factored form. In this article, we will answer some frequently asked questions about quadratic equations in factored form.

Q: What is the difference between factored form and standard form?

A: The factored form of a quadratic equation is a product of two binomials, each of which is a linear expression. The standard form of a quadratic equation is a polynomial expression with a leading coefficient of 1. For example, the factored form of the quadratic equation y = x^2 - 4x - 3 is (x - 3)(x + 1), while the standard form is x^2 - 4x - 3.

Q: How do I determine the x-intercepts of a quadratic equation in factored form?

A: To determine the x-intercepts of a quadratic equation in factored form, you need to set the equation equal to zero and solve for x. This will give you the values of x that make the equation equal to zero, which are the x-intercepts.

Q: How do I determine the vertex of a quadratic equation in factored form?

A: To determine the vertex of a quadratic equation in factored form, you need to find the x-coordinate of the vertex, which is the average of the x-intercepts. You can then plug this value into the equation to find the y-coordinate of the vertex.

Q: Can I graph a quadratic equation in factored form if it has complex roots?

A: Yes, you can graph a quadratic equation in factored form even if it has complex roots. However, you will need to use the complex conjugate of the root to find the x-intercepts.

Q: How do I graph a quadratic equation in factored form if it has a negative leading coefficient?

A: If the quadratic equation has a negative leading coefficient, the parabola will open downward. To graph the parabola, you can use the x-intercepts and the vertex to draw a smooth curve.

Q: Can I use the factored form of a quadratic equation to find the equation of a circle?

A: No, the factored form of a quadratic equation is only used to graph quadratic equations, not to find the equation of a circle.

Q: How do I convert a quadratic equation from standard form to factored form?

A: To convert a quadratic equation from standard form to factored form, you need to factor the quadratic expression. This can be done by finding two numbers whose product is the constant term and whose sum is the coefficient of the linear term.

Q: Can I use the factored form of a quadratic equation to find the equation of a parabola in three dimensions?

A: No, the factored form of a quadratic equation is only used to graph quadratic equations in two dimensions, not in three dimensions.

Q: How do I graph a quadratic equation in factored form if it has a rational root?

A: If the quadratic equation has a rational root, you can use the factored form to graph the parabola. You will need to find the x-intercepts and the vertex to draw a smooth curve.

Q: Can I use the factored form of a quadratic equation to find the equation of a hyperbola?

A: No, the factored form of a quadratic equation is only used to graph quadratic equations, not to find the equation of a hyperbola.

Conclusion

In this article, we answered some frequently asked questions about quadratic equations in factored form. We hope that this article has been helpful in clarifying any confusion you may have had about graphing quadratic equations in factored form.

Example Problems

Graph the quadratic equation y = (x - 2)(x + 3).
Graph the quadratic equation y = -\frac{1}{2}(x - 1)(x + 2).
Graph the quadratic equation y = x^2 - 4x - 3.

Solutions

To graph the quadratic equation y = (x - 2)(x + 3), we need to identify the x-intercepts and the vertex. The x-intercepts are x = 2 and x = -3, and the vertex is the point (0.5, -1.5).
To graph the quadratic equation y = -\frac{1}{2}(x - 1)(x + 2), we need to identify the x-intercepts and the vertex. The x-intercepts are x = 1 and x = -2, and the vertex is the point (-0.5, 0.5).
To graph the quadratic equation y = x^2 - 4x - 3, we need to identify the x-intercepts and the vertex. The x-intercepts are x = -1 and x = 3, and the vertex is the point (1, -4).

Final Thoughts

Graphing quadratic equations in factored form is a useful skill for students and professionals alike. By understanding the x-intercepts and the vertex, we can graph the parabola and understand its behavior. In this article, we answered some frequently asked questions about quadratic equations in factored form and provided example problems and solutions to help readers practice graphing quadratic equations in factored form.