point slope form

Question

A line passes through the point 2,-7 and has a slope of -9.

Write an equation in point-slope form for this line.

Answer 1

set slope = slope = "rise over run" = the difference in y coordinates divided by differences in x coordinates.

(y+7)/(x-2) = -9

multiply both sides by x-2

y+7 = -9x + 18

subtract 7 from both sides

y = -9x + 11 is the equation of the line in slope intercept form which is y=mx+b where m=-9 and b=11