Question 372233
<font face="Garamond" size="+2">


It isn't.  *[tex \Large x\ -\ 4] is simply a binomial expression in one variable.  Now if you make it equal to something, such as zero, THEN you have an equation whose graph and/or solution set is a straight line, and in this particular case, a vertical line.


The reason it is a vertical line is that the set of points that comprise the solution set of the equation all have an ordinate, or *[tex \Large x]-coordinate, of the value 4.  All points with an *[tex \Large x]-coordinate of 4 must lie on a vertical line.  Go ahead and try to find a point with an *[tex \Large x]-coordinate of 4 that is NOT on the vertical line *[tex \Large x = 4].


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
<div style="text-align:center"><a href="http://outcampaign.org/" target="_blank"><img src="http://cdn.cloudfiles.mosso.com/c116811/scarlet_A.png" border="0" alt="The Out Campaign: Scarlet Letter of Atheism" width="143" height="122" /></a></div>
</font>