Question 1130988
<pre>
9x-7y=-7 doesn't do anything called "come out x=1. y=16/7'.

You see, 9x-7y=-7 is ALGEBRA for this graphed line of GEOMETRY,
and the only thing that can be said about "x=1 and "y=16/7" is
that if you substitute 1 for x in 9x-7y=-7 you will get y = 16/7.

   9x - 7y = -7
 9(1) - 7y = -7
    9 - 7y = -7
   -9        -9
---------------
       -7y = -16
   {{{(-7y)/(-7)}}}{{{""=""}}}{{{(-16)/(-7)}}}
         y = {{{16/7}}} 

And what that means is that the point (1, 16/7) is one of the 
points on the line which has 1 as its x coordinate and 16/7 as 
its y-coordinate:

{{{drawing(400,400,-5,5,-5,5,
graph(400,400,-5,5,-5,5),line(-14,-17,7,10),
circle(1,16/7,.1), circle(1,16/7,.09),
circle(1,16/7,.08),circle(1,16/7,.07),circle(1,16/7,.05), circle(1,16/7,.03),locate(1,16/7,

(matrix(1,3,1,",",16/7)))

  )}}}

{{{drawing(400,400,-5,5,-5,5,
graph(400,400,-5,5,-5,5),line(-14,-17,7,10),
green(line(0,16/7,1,16/7),line(1,0,1,16/7)),
circle(1,16/7,.1), circle(1,16/7,.09),
circle(1,16/7,.08),circle(1,16/7,.07),circle(1,16/7,.05), circle(1,16/7,.03),locate(1,16/7,



(matrix(1,3,1,",",matrix(1,1,16/7=2&2/7))))

  )}}}


Edwin</pre>