Find the value of c such that the three points (5,5), (3,1) and (6,c) lie on the same line.
Note: Three points are on the same line if the slope of the line through any two points is always the same.
+2666 Note that the formula for slope is: \({ \text{rise} \over \text{run}} = {{y_2 - y_1 \over x_2 - x_1}}\)
Substituting the 2 points we know, we find the slope is: \({ 5 - 1 \over 5 - 3} = {4 \over 2} = 2 \)
This means that the y-coordinate for x = 6 is 2 higher than the y-coordinate when x = 5.
Can you take it from here?
