Respostas

2014-06-10T07:08:17-03:00
 \left \{ {{-x+y=8} \atop {x=3y}} \right.
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Vc pode somar x com x e y com y neste caso !
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 \left \{ {{-x+y=8} \atop {x-3y=0}} \right.
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 \left \{ {{-x+x=0} \atop {y+(-3y)=-2y}} \right.
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Sendo que 8+0=8
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-2y=8 ;y= \frac{8}{-2}=>y= -4
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 \left \{ {{y=-4} \atop {x=3y}} ;x=3*(-4);x=-12\right.
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 \left \{ {{-x+y=8} \atop {-(-12)+(-4)=8}}==>+12-4=8\right.
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Portanto :  \left \{ {{y=-4} \atop {x=-12}} \right.
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