Question

Find the magnitude of u+v,if u =4i - 2j + 4k and v = 3i - 6j - 2k

Answer 1

$u + v = (4 + 3)i + ( - 2 - 6)j + (4 - 2)k \\ = 7i - 8j + 2k \\ |u + v| = \sqrt{ {7}^{2} + {( - 8)}^{2} + {2}^{2} } \\ = \sqrt{117} = 3 \sqrt{13}$