Respostas

2014-08-24T12:21:10-03:00
3x+y=5 e x+3y=-1
3x+y=5=> y=5-3x

x+3y=-1=> x+3*(5-3x)=-1=> x+15-9x=-1=> -8x=-1-15=> -8x=-16 *(-1) =>8x=16=> x=16/8=> x=2

y=5-3x=> y=5-3*2=> y=5-6=> y=-1
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2014-08-24T13:11:57-03:00
 3x+ y = 5

x+ 3y = -1 \left \{ {{y=2} \atop {x=2}} \right.

# x+ 3y = -1
  x=-3y-1
 x= -3(-1) -1
 x=3-1
x=2

3x+ y = 5
  3(-3y-1)+y=5
 -9y-3+y=5
 -8y=5+3
 y= 8/-8
 y= -1
1 5 1