# Math Help - Unit Vectors - M1

1. ## Unit Vectors - M1

I don't really know if this belongs here, but I couldn't find anwhere to put it. All help appreciated.

Given that vector a = i - 2j and vector b = -3i + j find:

a) p, if 'a + xb' is parallel to -i - 3j
b) q, if 'qa + b' is parallel to 2i + j

2. 2 vectors $v=v_1i+v_2j,w=w_1i+w_2j$ are parallel iff $\frac{v_1}{w_1}=\frac{v_2}{w_2}$. After computing a+pb we get $(1-3p)i+(p-2)j$ and with the condition of parallelism we have that $\frac{1-3p}{-1}=\frac{p-2}{-3}$, from where we have $p=\frac{1}{2}$, for a).