What is the point slope form for (-12,8) and (9,15)

Answer 1

The generic point slope form of a line that passes through a point (x₁, y₁) is (y - y₁) = m(x - x₁). We can plug in either point for (x₁, y₁) but the problem is, we don't have the slope (m). So first find the slope.

Slope is given by m = (y₂ - y₁)/(x₂ - x₁) so, if we say Point 1 is (-12, 8) and Point 2 is (9, 15), then:

m = (15 - 8)/(9 - -12) = 7/21 = 1/3

Lets pick (9, 15) as the point we plug into the generic point slope form (y - y₁) = m(x - x₁) so:

(y - 15) = 1/3(x - 9)