Respostas

2014-05-26T10:25:44-03:00
(x-1) + 6x + 6 - 5
x - 1 + 6x + 1
x + 6x
7x 

b) 2(x + 10) - (x2 - 1)
2x + 20 - x2 + 1
x2 + 2x + 21