Question

Im trying to do IXL and I dont understand the way my teacher teaches (ironic right?)

the points (-9,-3) and (-2,r) fall on a line with a slope of 1/7. What is the value of r?
If its not right im gonna report you

Answer 1

r = - 2

Explanation:

Calculate the slope m using the slope formula and equate to
`(1)/(7)`

m =
`(y_(2)-y_(1) )/(x_(2)-x_(1) )`

with (x₁, y₁ ) = (- 9, - 3) and (x₂, y₂ ) = (- 2, r)

m =
`(r+3)/(-2+9)` , that is

`(r+3)/(7)` =
`(1)/(7)` ( cross- multiply )

7(r + 3) = 7 ( divide both sides by 7 )

r + 3 = 1 ( subtract 3 from both sides )

r = - 2