Respostas

2013-06-04T10:03:08-03:00

(a²-4a)(a²-8)

a⁴ -4a-8

2a⁴=-8/4

2a⁴=-2

a⁴=-2/2

a=-1

2013-06-04T10:04:21-03:00

se a =-1

(-1-2)(-1-4)

(-3)(-5)

+15

regras de sinais

(-)(-)=+

(-)(+)=-

(+)(-)=-

(+)(+)+