Question

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

A. y = 4x - 3
B. y = 4x - 2
C. y = 1/4x - 3
D. y = 1/4x - 2

Answer 1

C

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 ) = (4, - 2) and (x₂, y₂ ) = (- 4, - 4)

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

y =
`(1)/(4)` x + c ← is the partial equation

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

Using (- 4, - 4), then

- 4 = - 1 + c ⇒ c = - 4 + 1 = - 3

y =
`(1)/(4)` x - 3 → C