Diket vektor a=3i-2j, b=-i+4j, dan r=7i-8j. Jika vektor r = ka + mb maka hasil dari k+m adalah??? Tolong bantu yaa

r = ka + mb

[tex] \left[\begin{array}{ccc}7\\-8\end{array}\right] = k\left[\begin{array}{ccc}3\\-2\end{array}\right] + m \left[\begin{array}{ccc}-1\\4\end{array}\right] \\ \\ \left[\begin{array}{ccc}7\\-8\end{array}\right] = \left[\begin{array}{ccc}3k-m\\-2k+4m\end{array}\right][/tex]

3k-m = 7
m = 3k-7

Substitusi
-2k + 4m = -8
-2k + 4(3k - 7) = -8
-2k + 12k - 28 = -8
10k = 20
k = 2

m = 3k - 7
m = 3(2) - 7 = -1

k+m = 2+(-1) = 1