Question

The points (4, -6) and (r, 6) lie on a line with slope 3. Find the missing coordinate r.

Answer 1

r = 8

Explanation:

Calculate the slope m using the slope formula and equate to 3

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

with (x₁, y₁ ) = (4, - 6) and (x₂, y₂ ) = (r, 6)

m =
`(6+6)/(r-4)` =
`(12)/(r-4)` , then

`(12)/(r-4)` = 3 ( multiply both sides by (r - 4))

12 = 3(r - 4) ← divide both sides by 3

4 = r - 4 ( add 4 to both sides )

8 = r