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Question 58698: Write the equation of the line passing through (3, –7) and (–6, –7)
Answer by funmath(2933)   (Show Source):
You can put this solution on YOUR website! Write the equation of the line passing through (3, –7) and (–6, –7)
There are two kinds of special lines, vertical lines and horizontal lines. Notice that y=-7 in both points, if you were to plot both these points and connect them, you would have a horizontal line going through y=-7. The equation of the horizontal line going through y=-7 is  .
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If you didn't notice that the y was the same in both points, if you tried to find the slope of the line between these two points using the slope formula: you'd get:
If you remember that horizontal lines have a slope of 0, you can now say that the equation of the line is y=-7.
If you don't remember, you're still ok. When you try to make the equation of a line using the point-slope formula: , with m=0 and (x1,y1)=(3,-7)
You get 
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(This special case you can get by with not memorizing, but you can't get by with not memorizing the special case involving vertical lines. When the x's of two points are the same the equation of the line is x=k, k is what ever x that the points share.)
Happy Calculating!!!
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