dik: a=3i-2j, b=-i+4j dan r=7i-8j. jika r=ka+mb,maka nilai k dan m adalah

r = ka+mb
( 7, -8) = k(3, -2) + m(-1, 4)
didapat persamaan:
(i) 3k - m = 7 [kalikan 4]
(ii) -2k+4m = -8 [kslikan 1]

12k - 4m = 28
-2k +4m = -8
------------------- +
10k = 20
k = 2

subtitusi k = 2 ke persamaan (i)
3k - m = 7
3(2) - m = 7
6 - m = 7
-m = 7-6
-m = 1
m = -1

jadi k = 2 dan m = -1