Equation of a line passing through two points

HOME

Math Central

Quandaries & Queries

Question from Kenzie, a student:

Hi. I am having problems solving an equation of the line passing through (-2,4) and (6,0)

This is what I did so, far: y-4= -1/2x +1
LCD multiplied by2 2y-8=x+2
2Y-8-X+8=2+8
2Y-X=10
-X+2Y=10

BUT, THE ANSWER SHOULD BE: Y= -1/2+3

Kenzie, we have two responses for you:

Hi Kenzie,

Check the first step

y - 4 = -1/2(x - (-2)) = -1/2x - 1

Penny

Kenzie,

How are you starting it? You should use:

(y - y₀) = [ (y₁ - y₀) / (x₁ - x₀) ] (x - x₀)

and since (x₀, y₀) = (-2, 4) and (x₁, y₁) = (6, 0), you should substitute in and get:

(y - 4) = [ (0 - 4) / (6 - (-2)) ] (x - (-2))

Did you forget the minus sign on the -2?

Stephen La Rocque. >

Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.