Respostas

2013-09-06T16:59:26-03:00
(4x+5)*(4x-5) = 4x*4x + 4x*(-5) + 5*4x + 5*(-5) = 16x -20x+ 20x - 25
16x - 25 =0
x = 25/16
2013-09-06T18:29:03-03:00
16x^2 - 20x +20x - 25 = 16x^2 - 25
(= espero q esteja claro!!!