equation of line when two points are given - Find the equation of the line that passes through the points (-800, 200) and (-400, 300).

Sangeetha Pulapaka (last edited 3 years ago) (Expert, Educator @Qalaxia)

STEP 1:

Recall how to find the slope of a line from two points.

Given points are (-800,200) and (-400,300)

m = \frac{y_{2}-y_{1}}{x_{2}-x_{1}}

m = \frac{300-200}{-400 -(-800)}

m = \frac{100}{400}

m = \frac{1}{4}

STEP 2:

Find the y-intercept

Plug in this value of the slope m and any one set of points to find the y-intercept

Substituting m = \frac{1}{4}, x = -800 , y = 200

in y = mx+b

200 = \frac{1}{4}\times-800 + b

200 = -200 +b

b = 400

STEP 3:

Write the equation of the line

Plug in the value of m = \frac{1}{4} and b = 400 to get

y = \frac{1}{4}x + 400