\[5x^{2} - 9x + 4 = 0\]
\[D = 81 - 80 = 1\]
\[x_{1} = \frac{9 + 1}{10} = 1;\ \]
\[x_{2} = \frac{9 - 1}{10} = \frac{8}{10} = 0,8.\]
\[Ответ:x = 0,8;x = 1.\]