Решите уравнение: x^2-9x+20=0.

\[x² - 9x + 20 = 0\]

\[D = ( - 9)^{2} - 4 \cdot 1 \cdot 20 =\]

\[= 81 - 80 = 1\]

\[x_{1} = \frac{9 + \sqrt{1}}{2 \cdot 1} = \frac{9 + 1}{2} = \frac{10}{2} = 5\]

\[x_{2} = \frac{9 - \sqrt{1}}{2 \cdot 1} = \frac{9 - 1}{2} = \frac{8}{2} = 4\]

\[Ответ:x = 5;x = 4.\]