\[(5x + 1)^{2} = 4\]
\[(5x + 1)^{2} = 2^{2}\]
\[5x + 1 = 2\]
\[5x = 1\]
\[x = \frac{1}{5} = 0,2.\]
\[5x + 1 = - 2\]
\[5x = - 3\]
\[x = - \frac{3}{5} = - 0,6.\]
\[Ответ:x = - 0,6;x = 0,2.\]