Question

Given points (2,4) and(1,-5), write an equation in slope intercept form

Answer 1

y = 9x - 14

Explanation:

the equation of a line in slope- intercept form is

y = mx + c ( m is the slope and c the y-intercept )

to calculate m use the gradient formula

m = ( y₂ - y₁ ) / ( x₂ - x₁ )

with (x₁, y₁ ) = (2, 4) and (x₂, y₂ ) = (1, - 5)

m =
`(-5-4)/(1-2)` =
`(-9)/(-1)` = 9, hence

y = 9x + c ← is the partial equation

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

using (2, 4 ), then

4 = 18 + c ⇒ c = 4 - 18 = - 14

y = 9x - 14 ← equation in slope- intercept form