4阶行列式计算公式是(a1b2-a2b1)(c3d4-c4d3)-(a1b3-a3b1)(c2d4-c4d2)+(a1b4-a4b1)(c2d3-c3d2)+(a2b3-a3b2)(c1d4-c4d1)-(a2b4-a4b2