解三元一次方程 {y=2x-1 {3x+y+5z=9 {x+2y=3z=6 {x+y+z=26 {x-y=1 {2x-y+z=18

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解三元一次方程 {y=2x-1 {3x+y+5z=9 {x+2y=3z=6 {x+y+z=26 {x-y=1 {2x-y+z=18
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解三元一次方程 {y=2x-1 {3x+y+5z=9 {x+2y=3z=6 {x+y+z=26 {x-y=1 {2x-y+z=18
解三元一次方程 {y=2x-1 {3x+y+5z=9 {x+2y=3z=6 {x+y+z=26 {x-y=1 {2x-y+z=18

解三元一次方程 {y=2x-1 {3x+y+5z=9 {x+2y=3z=6 {x+y+z=26 {x-y=1 {2x-y+z=18
{y=2x-1 (1)
3x+y+5z=9 (2)
x+2y+3z=6 (3)
(2)*3-(3)*5得
9x+3y+15z-5x-10y-15z=9*3-6*5
4x-7y=-3
4x-7(2x-1)=-3
4x-14x+7=-3
-10x=-10
x=1
y=1
z=1
{x+y+z=26 (1)
x-y=1 (2)
2x-y+z=18 (3)
(1)-(3)得
x+y+z-2x+y-z=26-18
-x+2y=8 (4)
(2)+(4)得
y=9
x=10
z=7