Determine the vector operation A + B:

Rewrite our vectors in terms of coordinates:

(a1, a2, a3) = (1, 2, 3)
(b1, b2, b3) = (4, 5, 6)

Add the respective vector components:

A + B = (a1 + b1 , a2 + b2 , a3 + b3 )
A + B = (1 + 4, 2 + 5, 3 + 6)
A + B = (5, 7, 9)

Expresed in vector format, we have:

5
7
9
Calculate the length (magnitude) of A + B

Rewrite the vector in terms of coordinates:

(a + b1, a + b2, a + b3) = (5, 7, 9)

The formula for this is below:

||A + B|| = Square Root(a + b12 + a + b22 + a + b32)
||A + B|| = Square Root(52 + 72 + 92)
||A + B|| = √25 + 49 + 81
||A + B|| = √155
||A + B|| = 12.449899597989