Equation of a line parallel to the x-axis or y-axis

Lesson icon
Lesson Objective
This lesson shows you how to determine the equation of a line that is parallel to the x-axis or y-axis.
Sponsored Links
Why icon
About This Lesson
In this lesson, we will learn how to determine the equation of a line that is parallel to the x-axis or y-axis.

This lesson shows you the concepts that you should know about a line that is parallel to the x-axis or y-axis of the coordinate plane. Also, we will see some examples on determining its equation.

You should proceed by reading the study tips and watch the math video below. After that, you can try out the practice questions.
equation of parallel line

Study Tips

Tips icon
Tip #1
For a line that is parallel to the x-axis, the equation for such a line is:

          y = b      where b is some constant

Now, notice that b is the value of the
y-coordinate of any point on the line. For example, if b = -2, the equation of the line parallel to the x-axis will be:

                         y = -2

The math video below will show you the reason behind this.
equation of a line parallel to the x-axis
Tips icon
Tip #2
Similarly, for a line that is parallel to the
y-axis, the equation for such a line is:

              x = a   where a is some constant

Also, notice that a is the value of the
x-coordinate of any point on the line. For example, if a = 1, the equation of the line parallel to the x-axis will be:

                         x = 1

The math video below will show you the reasons behind this.
equation of a line parallel to the y-axis
Tips icon
Tip #3
Usually, the equation of a line parallel to the x-axis is written this way:

                                    y = 1            

For some cases, you may come across the equation above written in this form instead:
                                   y -1 = 0

Now, these two equations are in fact the same, this is because if we add +1 to both sides of the equation, we have:

                              y -1 +1 = 1
                                     y   = 1

So, we can see that there is no difference between these two equations. This explanation also applies to the equation of a line parallel to the y-axis.
Now, watch the following math video to learn more.

Math Video

Math video icon
Click play to watch video
Sponsored Links
 
Math videos icon
Math Video Transcript

Practice Questions & More

Math video icon
Multiple Choice Questions (MCQ)
Now, let's try some MCQ questions to understand this lesson better.

You can start by going through the series of questions equation of a line parallel parallel to the x-axis or y-axis or pick your choice of question below.
  1. Question 1 on determining the equation of a line using the coordinates of two points.
Math video icon
Site-Search and Q&A Library

Please feel free to visit the Q&A Library. You can read the Q&As listed in any of the available categories such as Algebra, Graphs, Exponents and more. Also, you can submit math question, share or give comments there.
share icon
Share This Page
iPod Touch & iPhone
iPad
Graphs & Equations
Algebra
Exponents
Symmetry
Fractions
Measurements
Interest
Angles
Triangles
Useful Resources