# Video: Determining an Equation That Represents a Line Parallel to the π₯-Axis

Which of the following equations represents a line parallel to the π₯-axis? [A] β9π¦ β 7 = 0 [B] β2π₯ β π¦ = 0 [C] βπ₯ β 5π¦ = 3 [D] 8π₯ + 3π¦ = β9.

01:39

### Video Transcript

Which of the following equations represents a line parallel to the π₯-axis? Is it A) negative nine π¦ minus seven equals zero, B) negative two π₯ minus π¦ equals zero, C) negative π₯ minus five π¦ equals three, or D) eight π₯ plus three π¦ equals negative nine?

The π₯-axis is horizontal. Any line that is parallel to this must also be horizontal. All of these lines will have equation π¦ equals π, where π is a constant that can be found where the line intercepts the π¦-axis.

Options B, C, and D all contain an π₯ term. Therefore, none of those equations can be parallel to the π₯-axis. Option A, on the other hand, only contains a π¦ term and a constant. This can be rewritten in the form π¦ equals π. Adding nine π¦ to both sides of the equation gives us negative seven is equal to nine π¦. And, finally, dividing both sides of this equation by nine gives us π¦ is equal to negative seven-ninths. Equation A will be parallel to the π₯-axis and will intercept the π¦-axis at negative seven-ninths.