− t 2 t 1 3 + t 4 t 1 3 + 2 t 2 t 3 t 1 2 − t 3 t 1 2 + t 2 t 4 t 1 2 − t 2 t 3 t 4 t 1 2 − 2 t 4 t 1 2 + t 1 2 − 2 t 2 t 3 t 1 + t 3 t 1 − t 2 t 4 t 1 + t 2 t 3 t 4 t 1 + 2 t 4 t 1 − t 1 + t 2 t 3 − t 3 t 4 {\displaystyle -t2t1^{3}+t4t1^{3}+2t2t3t1^{2}-t3t1^{2}+t2t4t1^{2}-t2t3t4t1^{2}-2t4t1^{2}+t1^{2}-2t2t3t1+t3t1-t2t4t1+t2t3t4t1+2t4t1-t1+t2t3-t3t4}
