Question

Write the equation of the line that passes through (2,-4) and (-1,-1)

Answer 1

y = - x - 2

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 ) = (2, - 4) and (x₂, y₂ ) = (- 1, - 1)

m =
`(-1+4)/(-1-2)` =
`(3)/(-3)` = - 1 , thus

y = - x + c ← is the partial equation

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

Using (- 1, - 1 ), then

- 1 = 1 + c ⇒ c = - 1 - 1 = - 2

y = - x - 2 ← equation of line

Answer 2

You need to use the y = mx + b formula which will get you to the answer
y = -x -2