Question

Show that |a|+|b|=|a+b|, if a and b have opposite directions...?

Answer 1

\[|\begin{matrix}\rightarrow \\ a\end{matrix}|+|\begin{matrix}\rightarrow \\ b\end{matrix}|=|\begin{matrix}\rightarrow \\ a\end{matrix}+\begin{matrix}\rightarrow \\ b\end{matrix}|\]
if\[\begin{matrix}\rightarrow \\ a\end{matrix}\] and \[\begin{matrix}\rightarrow \\ b\end{matrix}\] have opposite directions?

Answer 2

I really don't see how that's true

Answer 3

now LateX is down for me...

Answer 4

If a and b have opposite directions, then b=-ka, where k is a constant, right?