Question 177686
<FONT FACE="Times New Roman" SIZE="+2">Every point on the line *[tex \huge x = -8] has an x-coordinate of -8.  So if you calculate the slope, using:


*[tex \huge \frac {y_1 - y_2}{x_1 - x_2}],


the denominator is zero regardless of what two points on the line you select for *[tex \huge (x_1,y_1)] or *[tex \huge (x_2,y_2)].  Therefore the slope is undefined.  This is a vertical line.


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