Respostas

2014-04-29T18:11:27-03:00
a) 7x-4x+3x=3x+3x= 6x
b) 5xy+15xy-12xy+2xy=20xy-10xy=10xy
c) 13y-10y+7y+15y-6y
=10y+15y-6y=25y-6y=19y
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