Question 82663
{{{m = (y[2] - y[1]) / (x[2] - x[1])}}}
A = (2,6)
D = (-3, -3)
This is just a matter of getting the subscripts right (the 1's and 2's)
The given points are going to end up being ({{{x[1]}}}),({{{y[1]}}})
and ({{{x[2]}}}),({{{y[2]}}}).
You decide and either way it works. 
A = ({{{x[1]}}}),({{{y[1]}}})
D = ({{{x[2]}}}),({{{y[2]}}})
That will work fine, and also
A = ({{{x[2]}}}),({{{y[2]}}})
D = ({{{x[1]}}}),({{{y[1]}}})
That works fine, too
I'll do it both ways to prove it
A = (2,6)
(2,6) = ({{{x[1]}}}),({{{y[1]}}})
D = (-3, -3)
(-3, -3) = ({{{x[2]}}}),({{{y[2]}}})
{{{m = (y[2] - y[1]) / (x[2] - x[1])}}}
{{{m = (-3 - 6) / (-3 - 2)}}}
{{{m = (-9) / (-5)}}}
{{{m = 9/5}}}
-----------------------------
Now the other way
A = (2,6)
(2,6) = ({{{x[2]}}}),({{{y[2]}}})
d = (-3, -3)
(-3, -3) = ({{{x[1]}}}),({{{y[1]}}})
{{{m = (y[2] - y[1]) / (x[2] - x[1])}}}
{{{m = (6 - (-3)) / (2 - (-3))}}}
{{{m = (6 + 3) / (2 + 3)}}}
{{{m = 9/5}}}
So, you can't go wrong as long as you keep
straight which point is which. Hope this helps