Question

A line intersects the points (3,-4) and

(1, 2). What is the slope-intercept
equation for this line?
y = [?]x+ [?]

Answer 1

y = - 3x + 5

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 = (y₂ - y₁ ) / (x₂ - x₁ )

with (x₁, y₁ ) = (3, - 4) and (x₂, y₂ ) = (1, 2)

m =
`(2+4)/(1-3)` =
`(6)/(-2)` = - 3, thus

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

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

Using (1, 2), then

2 = - 3 + c ⇒ c = 2 + 3 = 5

y = - 3x + 5 ← equation of line