\[\boxed{\text{645\ (645).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ x² - 14x + 52 = 0\]
\[x^{2} - 14x + 49 + 3 = 0\]
\[(x - 7)^{2} + 3 = 0\]
\[(x - 7)^{2} = - 3\]
\[так\ как\ (x - 7)^{2} \geq 0\]
\[корней\ нет.\]
\[2)\ 4x² - 2x + 1 = 0\]
\[4x^{2} - 2x + \frac{1}{4} + \frac{3}{4} = 0\]
\[\left( 2x - \frac{1}{2} \right)^{2} + \frac{3}{4} = 0\]
\[\left( 2x - \frac{1}{2} \right)^{2} = - \frac{3}{4}\]
\[так\ как\ \left( 2x - \frac{1}{2} \right)^{2} \geq 0\]
\[нет\ корней.\]