Question

x+y+z=10
2x-y-2z=2
x+2z=4 me ajudem urgente

Answer 1

fazendo a 1 e a 2 
x +  y + z = 10    ( 1 )
2x - y - 2z = 2     ( 2 )
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 3x   //  - Z  = 12        ( 4 )

fazendo  a 3 com a 4 acima

x + 2z = 4    
3x - z  = 12 ( vezes   2  para eliminar z )
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 x  + 2z  = 4
6x - 2z   =24
 ----------------
7x   //    = 28
x = 28/7 = 4 *******
substitui na ( 4 )
3x - z = 12
3(4) - z = 12
12 - z = 12 
-z = 12 - 12 
-z = 0
z = 0 *******

x + y + z = 10
4 + y + 0 = 10
y = 10 - 4
y = 6 ****** 

Answer 2

$1)\ Resolu\c{c}\~ao \to \left\{\begin{array}{ccc}x+y+z=10\\2x-y-2z=2\\x+0y+2z=4\end{array}\right \to Escalonar$

$2)\  \left\{\begin{array}{ccc}x+y+z=10\\-3y-4z = -18\\-y+z=-6\end{array}\right \to \left\{\begin{array}{ccc}x+y+z=10\\-y+z = -6\\-7z = 0\end{array}\right \to \boxed{\boxed{z=0}}$

$3)\  \left\{\begin{array}{ccc}-y+z = -6\\\\-y+0 = -6\\\\\boxed{\boxed{y = 6}}\end{array}\right \to \left\{\begin{array}{ccc}x+y+z = 10\\\\x+6+0 = 10\\\\x = 10-6\\\\\boxed{\boxed{x=4}}\end{array}\right \to S=\{(x;y;z)\} = \{(4;6;0)\}$

Espero ter ajudado. =^.^=