Question

What is the eqaution of the line through (2, 3) and (- 1, 12) in the slope intercept form

Answer 1

y = - 3x + 9

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 ) = (2, 3) and (x₂, y₂ ) = (- 1, 12)

m =
`(12-3)/(-1-2)` =
`(9)/(-3)` = - 3, thus

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

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

Using (2, 3), then

3 = - 6 + c ⇒ c = 3 + 6 = 9

y = - 3x + 9 ← equation of line