Question

2a-b+c=3 a-b+2c=3 a+b+c=6

Answer 1

2a-b+c=3
a-b+2c=3
a+b+c=6
exercicio de matriz
$\left[\begin{array}{cccc}2&-1&1&3\\1&-1&2&3\\1&1&1&6\end{array}\right]$

2 -1 1 3
1 -1 2 3
1 1 1 6

1 0 -1 0  L1 = (1*L1) + (-1*L2)   
1 -1 2 3  L2 = (1*L2)
 1 1 1 6  L3 = (1*L3)  

1 0 -1 0  L1 = (1*L1)  
0 -1 3 3  L2 = (-1*L1) + (1*L2)
0 1 2 6   L3 = (-1*L1) + (1*L3)   

1 0 -1 0 L1 = (1*L1)
0 -1 3 3 L2 = (1*L2)
0 0 5 9  L3 = (1*L2) + (1*L3)  


-5  0 0 -9   L1 = (-5*L1) + (-1*L3)  
 0 -5 0 -12 L2 = (5*L2) + (-3*L3)
 0  0 5  9   L3 = (1*L3)     

 5 0 0 9      L1 = (-1*L1)   
 0 5 0 12    L2 = (-1*L2)  
 0 0 5 9      L3 = (1*L3)

sendo assim temos:
5a = 9   a = 9/5
5b = 12 b = 12/5
5c = 9   c = 9/5


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