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On line solution of multivariate equations：
    First set the elements of the equation (i.e. the number of unknowns), then click the "Next" button to enter the coefficients of each element of the equation set, and click the "Next" button to obtain the solution of the equation set.
    Note that the coefficients of each element of the equation system can only be numbers, not algebraic expressions (including mathematical functions).
    Current location：Equations > Multivariate equations > Answer
detailed information：
The input equation set is:
 x -2y -2z = 100    (1)
-9x + y -9z = 100    (2)
-1x -1y + z = 90    (3)
Question solving process:

Multiply both sides of equation (1) by 9, the equation can be obtained:
         9x -18y -18z = 900    (4)
, then add the two sides of equation (4) to both sides of equation (2), the equations are reduced to:
 x -2y -2z = 100    (1)
-17y -27z = 1000    (2)
-1x -1y + z = 90    (3)

Add both sides of equation (1) to both sides of equation (3) ,the equations are reduced to:
 x -2y -2z = 100    (1)
-17y -27z = 1000    (2)
-3y -1z = 190    (3)

Multiply both sides of equation (2) by 3
Divide the two sides of equation (2) by 17, the equation can be obtained:
        -3y - 
81
17
z = 
3000
17
    (5)
, then subtract both sides of equation (5) from both sides of equation (3), the equations are reduced to:
 x -2y -2z = 100    (1)
-17y -27z = 1000    (2)
 
64
17
z = 
230
17
    (3)

Multiply both sides of equation (3) by 459
Divide both sides of equation (3) by 64, get the equation：
         27z = 
3105
32
    (6)
, then add the two sides of equation (6) to both sides of equation (2), get the equation：
 x -2y -2z = 100    (1)
-17y = 
35105
32
    (2)
 
64
17
z = 
230
17
    (3)

Multiply both sides of equation (3) by 17
Divide both sides of equation (3) by 32, get the equation：
         2z = 
115
16
    (7)
, then add the two sides of equation (7) to both sides of equation (1), get the equation：
 x -2y = 
1715
16
    (1)
-17y = 
35105
32
    (2)
 
64
17
z = 
230
17
    (3)

Multiply both sides of equation (2) by 2
Divide both sides of equation (2) by 17, get the equation：
        -2y = 
2065
16
    (8)
, then subtract both sides of equation (8) from both sides of equation (1), get the equation：
 x = - 
175
8
    (1)
-17y = 
35105
32
    (2)
 z = 
115
32
    (3)

The coefficient of the unknown number is reduced to 1, and the equations are reduced to：
 x = - 
175
8
    (1)
 y = - 
2065
32
    (2)
 z = 
115
32
    (3)


Therefore, the solution of the equation set is:
x = - 
175
8
y = - 
2065
32
z = 
115
32


Convert the solution of the equation set to decimals:
x = -21.875000
y = -64.531250
z = 3.593750

解方程组的详细方法请参阅：《多元一次方程组的解法》
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