Question

Which is an equation for the line that contains the points (1, -2) and (-1,6) ?

A y = -2x + 4
B y = -4x - 2
C y = 2x - 4
D y = -4x + 2

Answer 1

D

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 ) = (- 1, 6 )

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

y = - 4x + c ← is the partial equation

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

Using (- 1, 6 ) , then

6 = 4 + c ⇒ c = 6 - 4 = 2

y = - 4x + 2 → D