Respostas

2014-08-22T23:07:16-03:00
3x+5=7=>3x=7-5=>x=2/3=>x=0,666...

2x-y/4=7=>(mmc=4)8x-y=28=>-y=28-8x*(-1)=>y=8x-28 e x=(y+28)/8

x+3x/7=7=>(mmc=7)7x+3x=49=>10x=49=>x=49/10=>x=4,9
2014-08-22T23:08:57-03:00
3x+5=7
3x=7-5
3x=2
x=2/3