Question 57243
I need to write the equation of the line passing through (6, -10) and (6, -6).
Notice that both the points have an x value of 6.  This is a special case.  
If you plotted these two points, you would have a vertical line going through x=6.
If you tried to find the slope of these two points using the slope formula {{{highlight(m=(y2-y1)/(x2-x1))}}} you'd have an undefined slope:
{{{m=(-6-(-10))/(6-6)}}}
{{{m=(-6+10)/0}}}
{{{m=4/0}}}  When 0 is in the denominator the fraction is undefined.
The equation with an undefined slope going through x=6 is:
{{{highlight(x=6)}}}
Happy Calculating, Ashley!!!