Question 908084
<pre>
find the value of r so that the line that passes through each pair of points has the given slope. (6,r), (3,3), m=2

This can be done the way the other person did it, but the slope formula (m) can be used too, as follows:
     {{{m = (y[2] - y[1])/(x[2] - x[1])}}}, when {{{system(matrix(1,5, "(", x[2], ",", y[2], ")") = matrix(1,2, "(3,", "3)"),
matrix(1,5, "(", x[1], ",", y[1], ")") = matrix(1,2, "(6,", "r)"))}}}

    {{{2 = (3 - r)/(3 - 6)}}} ---- Substituting {{{system(matrix(1,3, 2, for, m), matrix(1,3, 3, for, y[2]),
matrix(1,3, r, for, y[1]),
matrix(1,3, 3, for, x[2]),
matrix(1,3, 6, for, x[1]))}}}
    {{{2 = (3 - r)/(- 3)}}}
3 - r = - 6 ------ Cross-multiplying
  - r = - 6 - 3
  - r = - 9
   {{{highlight(r) = (- 9)/(- 1) = highlight(9))}}}</pre>