Question

The points (-4,2) and (4,r) lie on a line with slope -1. Find the missing cooridnate r

Answer 1

r = -6

Explanation:

The slope of a line is defined as

`m = (y_2 - y_1)/(x_2 - x_1)`

Let
`P_1(-4, 2)` and
`P_2(4, r)`. Since m = -1, we can write

`-1 = (r - 2)/(4 - (-4)) \Rightarrow -1 = (r - 2)/(8)`

or

`r - 2 = -8 \Rightarrow r = -6`