9 6 4 12

$\alwaysar{y^2 \ - \ yz \ - \ 0.25z^2}$ $\alwaysar{y^2 \ + \ yz \ - \ 0.25z^2}$ $\alwaysar{y^2 \ - \ yz \ + \ 0.25z^2}$ $\alwaysar{y^2 \ + \ yz \ - \ 0.5z^2}$