I hope this is the right forum.

The question is about vector addition. Suppose you have two vectors:

$\displaystyle u=<1,1,1>, v=<-1,2.1>$

The magnitudes are:

$\displaystyle ||u+v||=\sqrt{13}$ and

$\displaystyle ||u|| + ||v|| = \sqrt{3} + \sqrt{6}$

But the answer in the back of the book is showing $\displaystyle \sqrt{13}$ for both? Where am I going wrong?