− 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 -{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}}}
