First find the slope of the line segment joining (4,-2) and (9,-8). It is:
-8+2 -6
m = -------- = ------
9-4 5
Using slope-intercept form, y = mx + b:
-8 = (-6/5)(9) + b, or -8 = -54/9 + b.
Then b must be -8 = -54/9 + b. Solve for b:
-72 54 -18
----- - ----- = -------- = -2. Then y = mx + b becomes y = (-6/5)x - 2 (slope-
9 9 9 intercept form).
Point-slope form is y-k = m(x-h), where (h,k) is a point on the line.
Then y - (-8) = (-6/5)(x-9). This is in point-slope form.
