Given the points A(-5, k) and B(k, 7), find the value of k so that the slope of line AB is 2/7.

Answer 1

(7-k)/(k+5) = 2/7 cross multiply

49-7k = 2k+10 combine like terms

39=9k divide by 9

k = 39/9 = 13/3

Answer 2

(k-7)/(-5-k) = 2/7

7(k-7) = 2(-5-k)

7k - 49 = -10 - 2k

9k - 49 = -10

9k = 39

k = 39/9 = 13/3

check: (-5 , 13/3) vs ( 13/3, 7)

[ 7 - 13/3] / ( 13/3 - -5) =

[ 7 - 13/3] / ( 13/3 + 5) =

[ 21/3 - 13/3] divided by ( 13/3 +15/3) =

8/3 divided by 28/3 =

8/3 * 3/28 =

8/28 =

2/7

k=13/3