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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:
 A + 2B -5C = 0    (1)
 72B + 12C + 2D = 0    (2)
 12B + 8C -5D = 0    (3)
 B + C = 1    (4)
Question solving process:

Divide the two sides of equation (2) by 6, the equation can be obtained:
         12B + 2C + 
1
3
D = 0    (5)
, then subtract both sides of equation (5) from both sides of equation (3), the equations are reduced to:
 A + 2B -5C = 0    (1)
 72B + 12C + 2D = 0    (2)
 6C - 
16
3
D = 0    (3)
 B + C = 1    (4)

Divide the two sides of equation (2) by 72, the equation can be obtained:
         B + 
1
6
C + 
1
36
D = 0    (6)
, then subtract both sides of equation (6) from both sides of equation (4), the equations are reduced to:
 A + 2B -5C = 0    (1)
 72B + 12C + 2D = 0    (2)
 6C - 
16
3
D = 0    (3)
 
5
6
C - 
1
36
D = 1    (4)

Multiply both sides of equation (3) by 5
Divide the two sides of equation (3) by 36, the equation can be obtained:
         
5
6
C - 
20
27
D = 0    (7)
, then subtract both sides of equation (7) from both sides of equation (4), the equations are reduced to:
 A + 2B -5C = 0    (1)
 72B + 12C + 2D = 0    (2)
 6C - 
16
3
D = 0    (3)
 
77
108
D = 1    (4)

Multiply both sides of equation (4) by 576
Divide both sides of equation (4) by 77, get the equation：
         
16
3
D = 
576
77
    (8)
, then add the two sides of equation (8) to both sides of equation (3), get the equation：
 A + 2B -5C = 0    (1)
 72B + 12C + 2D = 0    (2)
 6C = 
576
77
    (3)
 
77
108
D = 1    (4)

Multiply both sides of equation (4) by 216
Divide both sides of equation (4) by 77, get the equation：
         2D = 
216
77
    (9)
, then subtract both sides of equation (9) from both sides of equation (2), get the equation：
 A + 2B -5C = 0    (1)
 72B + 12C = - 
216
77
    (2)
 6C = 
576
77
    (3)
 
77
108
D = 1    (4)

Multiply both sides of equation (3) by 2, get the equation：
         12C = 
1152
77
    (10)
, then subtract both sides of equation (10) from both sides of equation (2), get the equation：
 A + 2B -5C = 0    (1)
 72B = - 
1368
77
    (2)
 6C = 
576
77
    (3)
 D = 
108
77
    (4)

Multiply both sides of equation (3) by 5
Divide both sides of equation (3) by 6, get the equation：
         5C = 
480
77
    (11)
, then add the two sides of equation (11) to both sides of equation (1), get the equation：
 A + 2B = 
480
77
    (1)
 72B = - 
1368
77
    (2)
 6C = 
576
77
    (3)
 D = 
108
77
    (4)

Divide both sides of equation (2) by 36, get the equation：
         2B = - 
38
77
    (12)
, then subtract both sides of equation (12) from both sides of equation (1), get the equation：
 A = 
74
11
    (1)
 72B = - 
1368
77
    (2)
 C = 
96
77
    (3)
 D = 
108
77
    (4)

The coefficient of the unknown number is reduced to 1, and the equations are reduced to：
 A = 
74
11
    (1)
 B = - 
19
77
    (2)
 C = 
96
77
    (3)
 D = 
108
77
    (4)


Therefore, the solution of the equation set is:
A = 
74
11
B = - 
19
77
C = 
96
77
D = 
108
77


Convert the solution of the equation set to decimals:
A = 6.727273
B = -0.246753
C = 1.246753
D = 1.402597

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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