Question

Find the equation of the line shown

Answer 1

y = 2x

PRIMARY METHOD

Identify two points, find their slope, and write an equation

(1, 2) and (3, 6)

m = (y₂ - y₁)/(x₂ - x₁)

m = (6 - 2)/(3 - 1) = 4/2

m = 2

(1, 2)

y - y₁ = m (x - x₁)

y - 2 = 2 (x - 1)

y = 2x - 2 + 2

y = 2x

SIMPLER METHOD

Rise/Run

(0,0) to (1, 2) = 2/1 = 2

(1, 2) to (3, 6) = 4/2 = 2

Answer 2

y = 2x

Explanation:

The graph shows a straight line that passes trhough the origin, so it is a direct proportion relation with equation of the form y = mx.

To find the slope, use any easy-to-read point, and divide the y-coordinate by the x-coordinate. For example, use (1, 2).

m = 2/1 = 2

y = 2x