Question

Write an equation of the line that passes through the points (1, 2) and (4, 8)

Answer 1

2x-y=0 / y=2x

Explanation:

6x-3y=0, 2x-y=0

Answer 2

y = 2x

Explanation:

The equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y- intercept )

Calculate m using the slope formula

m =
`(y_(2)-y_(1) )/(x_(2)-x_(1) )`

with (x₁, y₁ ) = (1, 2) and (x₂, y₂ ) = (4, 8)

m =
`(8-2)/(4-1)` =
`(6)/(3)` = 2 , then

y = 2x + c ← is the partial equation

To find c substitute either of the 2 points into the partial equation

Using (1, 2 )

2 = 2 + c ⇒ c = 2 - 2 = 0

y = 2x ← equation of line