Respostas

2013-11-27T16:39:04-02:00
-(8a+4-3a-2) = 7a-3
-8a-4+3a+2 = 7a-3
-8a+3a-7a = -3+4-2
-12a = -1 .(-1)
12a = 1
a = 1/12