Video: Determining the Axis That Is Parallel to the Given Equation of a Straight Line

Video Transcript

Which axis is the straight line 𝑦 equals three parallel to?

First, we know that parallel lines do not intersect and they have the same slope. We have the equation 𝑦 equals three. If we think about the general form for a straight line 𝑦 equals 𝑚𝑥 plus 𝑏 and we have 𝑦 equals three, which means that we have a slope of zero. From there, if we sketch a 𝑦- and 𝑥-axis, graphing the line 𝑦 equals three would look like this. We should notice here that the line 𝑦 equals three crosses the 𝑦-axis. And we know that’s true because it has a 𝑏-value of three. And in the general form, the 𝑏 represents the 𝑦-intercept.

We can, therefore, say that the straight line 𝑦 equals three is not parallel to the 𝑦-axis because it intersects the 𝑦-axis. But we can say that 𝑦 equals three is parallel to the 𝑥-axis. The 𝑥-axis is the line where 𝑦 equals zero. The straight line 𝑦 equals three is parallel to the 𝑥-axis.