Question

Write an equation of the line that passes through (-7,9), (-5,3)

Answer 1

y = - 3x - 12

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 ) = (- 7, 9 ) and (x₂, y₂ ) = (- 5, 3 )

m =
`(3-9)/(-5-(-7))` =
`(-6)/(-5+7)` =
`(-6)/(2)` = - 3 , then

y = - 3x + c ← is the partial equation

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

using (- 5, 3 )

3 = 15 + c ⇒ c = - 3 - 15 = - 12

y = - 3x - 12 ← equation of line