x+2y+z=10(1)2x+3y-z=3(2)3x+2y+2z=17(3)(1)+(2)得3x+5y=13(4)2(2)+(3)得7x+8y=23(5)(4)和(5)得21x+35y=91(6)21x+24y=69(7)(6)-(7)得11y=22,所以y=2y=2代入（4）得y=2x=1,y=2代入（1）得z=5 所以解得x=1,y=2,z=5...