a= 3i + 4j - mk, b= 2i - 3j + 5k, jika a * b = 4. tentukan nilai m

Vektor

A(3,4,-m)
B(2,-3,5)

a.b = 4
3(2) +4(-3)+5(-m) = 4
6 -12 - 5m = 4
-6 - 5m = 4
-5m = 4+6 =10
m = 10/(-5)
m = -2
.