Question

Write the slope-intercept form equation of a line that passes through the points (-1,2) and (4,-8).

Answer 1

Answer: y=-2x

Step-by-step explanation: Use the slope formula

-8-2/4-(-1)

-10/5=-2

y=-2

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))` =
`(-10)/(4+1)` =
`(-10)/(5)` = - 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 + 0 , that is

y = - 2x ← equation of line