1 1 2 2 10 2 1 5 -12 0 3 -1 31 1 0 4 -1经过初等行变换,变成1 1 2 2 10 2 1 5 -10 -2 -1 -5 10 0 -2 2 -2变成1 1 2 2 10 2 1 5 -10 0 0 0 00 0 1 -1 1所以秩是3