Vectors - the sign of the coefficient? If we have two vectors, which we know have the relation:
$$r_1=-Br_2$$
Where B is a positive constant.
Then I believe we can say that:
$$|r_2|=|\frac{r_1}{-B}|$$
I thought that the magnitudes would then have the following relation:
$$|r_2|=\frac{|r1|}{B}$$
However, it is suggested in the exercises I have been doing that:
$$|r_2|=\frac{|r1|}{-B}$$
Am I correct?

Magnitudes are never negative, so your last equation can only be right if $B$ is always negative. At any rate, the precise statement of what we can conclude from that relation is:
$$
|r_2| = \frac{|r_1|}{|B|}
$$
If $B$ is a positive constant, then $|B| = B$.
(This is because $\left|\alpha \mathbf{v}\right| = |\alpha||\mathbf{v}|$, i.e. passing through the vector magnitude turns a scalar into its absolute value).
