求四阶行列式1,-1,5,0.-2,3,-8,-1.3,1-2,4.1,4,2,-5.横向

r2-r1,r3-3r1,r4-r1 1 2 3 4 0 -2 -2 -2 0 -7 -10 -12 0 0 -3 -9 r3-(7/2)r2 1 2 3 4 0 -2 -2 -2 0 0 -3 -5 0 0 -3-9 r4-r3 1 2 3 4 0 -2 -2 -2 0 0 -3 -5 0 0 0 -4 行列式 = -24