Question

The points (-12, 6) and (-4, r) lie on a line with slope - 1/2
Find the missing coordinate r.

Answer 1

r = 2

Explanation:

Slope formula:
`m=(y_2-y_1)/(x_2-x_1)\\`

Substitute the known values for their respective variables and solve for the missing coordinate, r.

`m=(y_2-y_1)/(x_2-x_1)\\\\ -(1)/(2)=(6-r)/(-12-(-4))\\\\-(1)/(2)=(6-r)/(-8)\\\\ -8(-(1)/(2))=((6-r)/(-8))-8\\\\ 4=6-r\\\\4-6=6-r-6\\\\-2=-r\\\\(-2)/(-1)=(-r)/(-1)\\\\ 2=r`