Question 204991:  Explain why the line x = 4 is a vertical line. 
 Answer by stanbon(75887)      (Show Source): 
You can  put this solution on YOUR website! Explain why the line x = 4 is a vertical line. 
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Plot two points where x = 4 such as (4,2) and (4,6) 
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Plot those two points and draw a line thru them. 
You will see that you get a vertical line. 
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Also, if you calculate a slope thru those points  
you will get (6-2)/(0) which is undefined.  That is 
the slope of a vertical line. 
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Cheers, 
Stan H. 
 
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