Inleiding veeltermen

\(-2xy-2y+xy-4y-2xy\)

\(\begin{align}-2xy-2y+xy-4y-2xy&=-2.xy-2.y+1.xy-4.y-2.xy\\&=-2.xy+1.xy-2.xy-2.y-4.y\\&=-3xy-6y\\\\ \end{align}\)