Advanced Slope Formula

Students are given the slope of a line, and are asked to find a coordinate "k" that is missing from one of the points that lies on the line. For example, if m = 4, and the line contains the points (3, 1) and (-2, k), find the value of k. To solve this problem, students substitute the given information into the slope formula, m = (y2 – y1)/(x2 – x1), to get 2 = (k – 1)/(-2 – 3), which simplifies to 2 = (k – 1)/-5. The next step is to multiply both sides of the equation by -5 to get rid of the fraction, to get –10 = k – 1, and adding 1 to both sides, -9 = k.