12-2 (1)当=时,A=-2-44→000 24-4 2x,+2x 同解方程组为{x2 x=k1+k20 0 8 2 (2)当=10时,4=-254011}011 245)(000 2~3 同解方程组为x2=-x3∴x=k 3 3(1) 当 = 1时,           − − − − − = 2 4 4 2 4 4 1 2 2 A           − → 0 0 0 0 0 0 1 2 2 同解方程组为      = = = − + 3 3 2 2 1 2 2 2 3 x x x x x x x           +          −  = 1 0 2 0 1 2 x k1 k2 (2) 当 = 10时,           − − = 2 4 5 2 5 4 8 2 2 A           → 0 0 0 0 1 1 2 4 5           → 0 0 0 0 1 1 1 0 2 1 同解方程组为      = = − = − 3 3 2 3 2 3 1 1 x x x x x x           − −  = 1 1 2 1 x k           − −  =  2 2 1 x k