27/ (2х+1)^2 = 3

(2x + 1)^2 = 27/3

(2x+1)^ 2 = 9

2x+1 = 3                или               2x+1 = -3

2x = 3-1                                       2x = -3 -1

2x = 2                                           2x = -4

x = 1                                             x = -2

Ответ: при х = 1; при х = -2