Question

A line has a slope of 9. One of the points on the line is (-2, p). Another point on the line is (2, 2p+1). Determine the value of p.

Answer 1

As we travel from (-2, p) to (2, 2p+1), x increases by 4 and y increases by p+1.  Note that -2 + 4 = 2 (which is correct), and that p + (p+1) = 2p+1 (which is also correct).                                                        

                                                                           p+1

Thus, the slope of this line is m = rise / run = -------- = 9

                                                                               4

Then p + 1 = 36, and p = 35.