Thank you for the opportunity to help you with your question!

For y = 6, this is a linear equation. Recall the slope-intercept form equation: y = mx + b

This can be rewritten as y = 0*x + 6 where m = 0 and b = 6 Here the x-intercept does not exist.

The y-intercept is b, which is b = 6 We see that y = 6 is a horizontal line that goes through the point (0, 6), (1, 6), (2, 6), (3, 6), (4, 6), (5, 6), (6, 6), etc...

For x = -4 this is a different situation. We cannot write it in slope-intercept form y = mx + b, because what becomes of the y variable? If we try to find the slope of this line pick two points say (-4, 1) and (-4, 2)

The slope would be m = (2-1)/(-4 - (-4)) = 1/0 which is UNDEFINED.

We have a vertical line here with x-intercept -4.

There is no y-intercept. The vertical line x = -4 goes through points (-4,0), (-4, 1), (-4, 2), (-4, 3), etc.

Please let me know if you need any clarification. I'm always happy to answer your questions.