Question

2 points in the line are (-4, 8) and (1,3)

Write the equation of each line described below in either slope - intercept form or point slope form.

Answer 1

y = - x + 4

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, 8 ) and (x₂, y₂ ) = (1, 3 )

m =
`(3-8)/(1-(-4))` =
`(-5)/(1+4)` =
`(-5)/(5)` = - 1 , then

y = - x + c ← is the partial equation

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

using (1, 3 ) , then

3 = - 1 + c ( add 1 to both sides )

4 = c

y = - x + 4 ← equation of line