Question 278354
find an equation for the line
through (-7,-4)and vertical.
<pre><font size = 4 color = "indigo"><b>
Let's plot that point and draw that vertical line through it: 

{{{drawing(400,400, -12,8,-10,10,

line(-7+.1,-4,-7-.1,-4), line(-7,-4+.1,-7,-4-.1), line(-7+.1,-4+.1,-7-.1,-4-.1), line(-7+.1,-4-.1,-7-.1,-4+.1), locate(-7,-4,"(-7,-4)"),

graph(400,400,-12,8,-10,10), green(line(-7,-11,-7,11)) )}}}

Let's look at some more points on that vertical line

{{{drawing(400,400, -12,8,-10,10,

line(-7+.1,-4,-7-.1,-4), line(-7,-4+.1,-7,-4-.1), line(-7+.1,-4+.1,-7-.1,-4-.1), line(-7+.1,-4-.1,-7-.1,-4+.1), locate(-7,-4,"(-7,-4)"),

line(-7+.1,4,-7-.1,4), line(-7,4+.1,-7,4-.1), line(-7+.1,4+.1,-7-.1,4-.1), line(-7+.1,4-.1,-7-.1,4+.1), locate(-7,4,"(-7,4)"),

line(-7+.1,-2,-7-.1,-2), line(-7,-2+.1,-7,-2-.1), line(-7+.1,-2+.1,-7-.1,-2-.1), line(-7+.1,-2-.1,-7-.1,-2+.1), locate(-7,-2,"(-7,-2)"),

line(-7+.1,7,-7-.1,7), line(-7,7+.1,-7,7-.1), line(-7+.1,7+.1,-7-.1,7-.1), line(-7+.1,7-.1,-7-.1,7+.1), locate(-7,7,"(-7,7)"),

line(-7+.1,-8,-7-.1,-8), line(-7,-8+.1,-7,-8-.1), line(-7+.1,-8+.1,-7-.1,-8-.1), line(-7+.1,-8-.1,-7-.1,-8+.1), locate(-7,-8,"(-7,-8)"),


graph(400,400,-12,8,-10,10), green(line(-7,-11,-7,11)) )}}}

What do you notice about all those points?  You notice that they
all have the same x-coordinate, which is -7.  So the equation is

"the line every point of which has x-coordinate = -7"

or writing that sentence much shorter, we have

x = -7

that is the equation of that vertical line.  You just write

what x (the x-coordinate) is always equal to on that line.

Edwin</pre>