解三元一次方程组(1)3x+y+2z=2,2x+y+3z=11,x-y-4z=-10(2)x/2=y/3=z/5,x-2y+3z=22.

Question

解三元一次方程组(1)3x+y+2z=2,2x+y+3z=11,x-y-4z=-10 (2)x/2=y/3=z/5,x-2y+3z=22.

Answer 1

第一道: 3x+y+2z=2 ………(1) 2x+y+3z=11………(2) x-y-4z=-10 ………(3) (2)+(3) 3x-z=1………(4) (1)-(2) x-z=-9………(5) (4)-(5) 2x=10 X=5 把X=5代入(5) 5-z=-9 Z=14 把X=5, Z=14代入(3) 5-y-4*14=-1 Y=-41 第二道；x/2=y/3=z/5………(1) x-2y+3z=22………(2) 有(1)得；设x=2k,y=3k,z=5k 把x=2k,y=3k,z=5k代入(2) 2k-6k+15k=22 K=2 把K=2代入 x=2k,y=3k,z=5k X=4,y=6,z=10