Jika a=2i - j + k dan b = -2j - 6k, maka (a+b)=...

2i - j + k => -j +(-2j)
-2j - 6k = -j - 2j
= -3j
=> k + (-6k)
= k - 6k
= -5k
jadi jawabanya 2i - 3j - 5k

a + b = (2,-1,1) + (0,-2,-6)
a + b = (2,-3,-5)
|a + b| = akar(2² + (-3)² + (-5)²)
|a + b| = akar38