Предмет: Математика, автор: 15mart04

Решить уравнение
x^2-2x-9=0

Ответы

Автор ответа: triolana

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Автор ответа: Svet1ana

$x^{2}-2x-9=0$

Cчитаем дискриминант:

$D=(-2)^{2}-4cdot1cdot(-9)=4+36=40$

Дискриминант положительный

$sqrt{D}=2sqrt{10}$

Уравнение имеет два различных корня:

$x_{1}=frac{2+2sqrt{10}}{2cdot1}=frac{2(1+sqrt{10})}{2}=1+sqrt{10}$

$x_{2}=frac{2-2sqrt{10}}{2cdot1}=frac{2(1-sqrt{10})}{2}=1-sqrt{10}$

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Решить уравнение
x^2-2x-9=0