Question

The point (5,4) and (X,8) lie on the same line. If the slope of the line is -2, what is the value of X? Show your work

Answer 1

x = 3

Explanation:

calculate the slope using the slope formula and equate the result to - 2

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

with (x₁, y₁ ) = (5, 4) and (x₂, y₂ ) = (x, 8)

m =
`(8-4)/(x-5)` =
`(4)/(x-5)` = - 2, thus

- 2(x - 5) = 4, that is

- 2x + 10 = 4 ( subtract 10 from both sides )

- 2x = - 6 ( divide both sides by - 2 )

x = 3