3Q
一定要有过程.1】x-2y=─92】3x-y+z=43】y=2x-74】4x+9x=12y-z=32x+3y-z=125x+3y+2z=23y-2z=12z+x=47x+y+z=63x-4z=47x+5z=4/194】x:y=3:25】x+y+z=266】x+y=37】x-y-z=2y:z=5:4x-y=1y+z=5y-z-x=─5x+y+z=662x-y+z=18z+x=6z-x-y=4