2x^2-4x-5=0

解答

2 x^{2} - 4 x - 5 = 0

x = \frac{2 + 14}{2}, x = \frac{2 - 14}{2}

十进制

x = 2.87082 \dots, x = - 0.87082 \dots

求解步骤

2 x^{2} - 4 x - 5 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 4 ) \pm ( - 4 ) ^{2} - 4 \cdot 2 ( - 5 )}{2 \cdot 2}

(- 4)^{2} - 4 \cdot 2 (- 5) = 214

x_{1, 2} = \frac{- ( - 4 ) \pm 2 14}{2 \cdot 2}

将解分隔开

x_{1} = \frac{- ( - 4 ) + 2 14}{2 \cdot 2}, x_{2} = \frac{- ( - 4 ) - 2 14}{2 \cdot 2}

x = \frac{- ( - 4 ) + 2 14}{2 \cdot 2} : \frac{2 + 14}{2}

x = \frac{- ( - 4 ) - 2 14}{2 \cdot 2} : \frac{2 - 14}{2}

二次方程组的解是:

x = \frac{2 + 14}{2}, x = \frac{2 - 14}{2}

f a c t or 10 a^{4} - a^{3} - 21 a^{2}

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