p2−q2p^{2}-q^{2}p2−q2
q2−p2q^{2}-p^{2}q2−p2
p2+q2\mathrm{p}^{2}+\mathrm{q}^{2}p2+q2
p2+2q2\mathrm{p}^{2}+2 \mathrm{q}^{2}p2+2q2
q2+2p2q^{2}+2 p^{2}q2+2p2