Question 207181
This is the ONLY kind of linear equation that CANNOT be put in slope-intercept form, because it is a vertical line and has no slope (not a slope of 0, that is horizontal, but its slope is undefined) -- pick two points on a vertical line, the rise will be something, the run will be 0, so rise / run will be undefined -- you can't divide by 0.

x-4=7     -->    x = 11.  In other words, this is all of the points, (x,y), such that the x coordinate is 11.
 
{{{graph(170,200,-2,15,-10,10, abs(x-11)<.1)}}}