Question

The points (-7,4) and (r,19) lie on a line with slope 3. Find the missing coordinate r.

Answer 1

r = -2

Explanation:

We can use the slope formula to find r.

m = ( y2-y1)/(x2-x1)

3 = ( 19-4)/(r- -7)

3 = 15/(r+7)

Multiply each side by (r+7).

3 ( r+7) = 15

Divide each side by 3.

r+7 = 15/3

r+7 = 5

Subtract 7 from each side.

r+7-7 = 5-7

r = -2