#$1004.$ Relative motion between particles

At a certain instant, particles

and

have position vectors and velocities given by:

Matlab$/$Octave

Mathematica

Python

R

SymPy

from sympy import $*$

rP $=$ Matrix$([-4,1])$

rQ $=$ Matrix$([-2,-3])$

vP $=$ Matrix$([6,2])$

vQ $=$ Matrix$([6,-7])$

What is the rate of change

of the distance between points

and

$?$