Explicação passo a passo:

2x-y+2z=8 >>>>>>>>>1

x+2y+4z=5 >>>>>>>>>>>2

3x+3y-z=7​>>>>>>>>>>>3

calculando >>>>1 e >>>>>>2

2x - 1y + 2z = 8 >>>>>>1

1x + 2y + 4z = 5 >>>>>>2 ( vezes - 2 )

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2x - 1y + 2z = 8 >>>>>>1

-2x - 4y - 8z = -10 >>>>>>2

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// - 5y - 6z = -2 >>>>>> ( - 1 )

5y + 6z = 2 >>>>>>>>>4

calculando >>>>>>2 com >>>>>>3

1x + 2y + 4z = 5 >>>>>>>>>>>2 ( vezes -3 )

3x + 3y - 1z = 7 >>>>>>>>>3

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- 3x - 6y - 12z = - 15

3x + 3y - 1z = 7

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// - 3y - 13z = - 8 ( - 1 )

3y + 13z = 8 >>>>>>5

calculando >>>>>>4 e >>>>>>5

5y + 6z = 2>>>>>>>>>>>4 ( vezes - 3 )

3y + 13z = 8>>>>>>>>5 ( vezes 5 )

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-15y - 18z = -6

15y + 65z = 40

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// + 47z = 34

z = 34/47 >>>>>resposta z

substituindo em >>>>>4 acima o valor de z por 34/47

5y + 6 ( 34/47) = 2

5y + 204/47 = 2/1

5y = 2/1 - 204/47 = ( 94 - 204)/47 = -110/47 >>>>>>>

y = - 110/47 : 5/1 ou - 110/47 * 1/5 = - 110/235 por 5 = - 22/47 >>>>>resposta y

substitui em >>>1 acima os valores de y por - 22/47 e z por 34/47

2x - ( - 22/47 ) + 2 ( 34/47 )= 8

2x + 22/47 + 68/47 = 8/1

2x + ( 22 +68)/47 = 8/1

2x + 90/47 =8/1

2X = 8/1 - 90/47

8/1 - 90/47 = ( 376 - 90)/47 =286/90>>>

2X /1 = 286/90

2X* 90 = 1 * 286

180X = 286

POR 2

90x = 143

x = 143/90 >>>>>>>>>>>resposta x