{3x-2y+5z=02x+5y-10z=192x+3y+15z=13{x+y=3y+z=5x+z=6

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{3x-2y+5z=02x+5y-10z=192x+3y+15z=13{x+y=3y+z=5x+z=6

{3x-2y+5z=02x+5y-10z=192x+3y+15z=13{x+y=3y+z=5x+z=6
{3x-2y+5z=0
2x+5y-10z=19
2x+3y+15z=13
{x+y=3
y+z=5
x+z=6

{3x-2y+5z=02x+5y-10z=192x+3y+15z=13{x+y=3y+z=5x+z=6
3x-2y+5z=0 (1)
2x+5y-10z=19 (2)
2x+3y+15z=13 (3)
(2)-(3) 得2y-25z=6 (4)
(2)*3-(1)*2得19y-40z=57 (5)
(4)*19-(5)*2得z=0
将z=0带入(4)得y=3
将y=3、z=0带入(3)得x=2
所以 x=2
y=3
z=0
补充:x+y=3 (1)
y+z=5 (2)
x+z=6 (3)
〔(1)+(2)+(3)〕÷2 得 x+y+z=7 (4)
(4)-(1)得 z=4
(4)-(2)得 x=2
(4)-(3)得 y=1