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Question 129845This question is from textbook
: A Horizontal line intersects a vertical line at (-3,7).Give the equation of each line in standard form. Trying to help my son with his homework,been 20 years since I had this stuff!! Thank you for your help.The book doesnt explain things all that much. Think we might be on the wrong track using the equation y=mx+b. Thanks again!!
This question is from textbook
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website! Horizontal lines have points where the y-coordinates are identical for every point in the line, and the x-coordinates can be any real number. They also have a zero slope, so  makes sense. Since all of the points have the same y-coordinate, the y-intercept must be (0,7), and then the equation would be  , or just 
Vertical lines are unique in that the slope is undefined, so doesn't make any sense. However, vertical lines are similar to horizontal lines except that it is the x-coordinate that remains constant and the y-coordinate can be any real number. So the equation is  , which is another way of saying, "I don't care what y is, as long as x is -3." Of course, you could make a similar descriptive statement for your vertical line.
Both of these equations are in standard form, because standard form is  . In the case of the horizontal line, A = 0, B = 1, and C = 7. In the case of your vertical line, A = 1, B = 0, and C = -3, and the terms with 0 coefficients simply go away, although you could actually write them out like so:
For your vertical line:  . However, that is trivial silliness.
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