Question 1099484
<pre>
First use the slope formula:
{{{m}}}{{{""=""}}}{{{(y[2]-y[1])/(x[2]-x[1])}}}
where (x<sub>1</sub>,y<sub>1</sub>) = (-9,7)
and where (x<sub>2</sub>,y<sub>2</sub>) = (9,-1)

{{{m}}}{{{""=""}}}{{{((-1)-(7))/((9)-(-9))}}}

{{{m}}}{{{""=""}}}{{{(-8)/(9+9)}}}

{{{m}}}{{{""=""}}}{{{(-8)/18}}}

{{{m}}}{{{""=""}}}{{{-4/9}}}

Now that you have the slope, use the point-slope formula:

{{{y-y[1]}}}{{{""=""}}}{{{m(x-x[1])}}}

where (x<sub>1</sub>,y<sub>1</sub>) = (-9,7)

[Don't substitute anything for variables x and y, but leave them
as they are and just substitute for x<sub>1</sub> and y<sub>1</sub>.]

{{{y-y[1]}}}{{{""=""}}}{{{m*(x-x[1])}}}
{{{y-7}}}{{{""=""}}}{{{expr(-4/9)*(x-(-9))}}}
{{{y-7}}}{{{""=""}}}{{{expr(-4/9)*(x+9)}}}
{{{y-7}}}{{{""=""}}}{{{expr(-4/9)*x-4}}}
{{{y}}}{{{""=""}}}{{{expr(-4/9)*x+3}}}

That's the slope y-intercept form.  If
you like you can get it into general form.
Multiply through by 9 to clear the fraction:

{{{9y}}}{{{""=""}}}{{{-4x+27}}}

{{{4x+9y}}}{{{""=""}}}{{{27}}}

Edwin</pre>