Question

Решите уравнение:x^2-5x+1=0

Answer 1

Ответ:

x²-5x+1=0

D = -5²-4 = 25-4 = 21

$x_{1} = \frac{5+\sqrt{21} }{2}$

$x_{2} = \frac{5-\sqrt{21} }{2}$

Answer 2

Ответ:

$\dfrac{5 \pm \sqrt{21}}{2}$

Объяснение:

${x}^{2} - 5x + 1 = 0$

$a = 1; \: \: b = - 5; \: \: c = 1$

$D = {b}^{2} - 4ac = {(- 5)}^{2} - 4 \cdot 1 \cdot 1 = 25 - 4 = 21 > 0; \: \: {x}_{1}, \: {x}_{2}$

${x}_{1, 2} = \dfrac{- b \pm \sqrt{D}}{2a} = \dfrac{ - (- 5) \pm \sqrt{21}}{2 \cdot 1} = \dfrac{5 \pm \sqrt{21}}{2}$