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受欢迎的代数 >

x-2x^2+7=0

解答

x - 2 x^{2} + 7 = 0

解答

x = - \frac{- 1 + 57}{4}, x = \frac{1 + 57}{4}

+1

十进制

x = - 1.63745 \dots, x = 2.13745 \dots

求解步骤

x - 2 x^{2} + 7 = 0

改写成标准形式

a x^{2} + b x + c = 0

- 2 x^{2} + x + 7 = 0

使用求根公式求解

x_{1, 2} = \frac{- 1 \pm 1 ^{2} - 4 ( - 2 ) \cdot 7}{2 ( - 2 )}

1^{2} - 4 (- 2) \cdot 7 = 57

x_{1, 2} = \frac{- 1 \pm 57}{2 ( - 2 )}

将解分隔开

x_{1} = \frac{- 1 + 57}{2 ( - 2 )}, x_{2} = \frac{- 1 - 57}{2 ( - 2 )}

x = \frac{- 1 + 57}{2 ( - 2 )} : - \frac{- 1 + 57}{4}

x = \frac{- 1 - 57}{2 ( - 2 )} : \frac{1 + 57}{4}

二次方程组的解是:

x = - \frac{- 1 + 57}{4}, x = \frac{1 + 57}{4}

作图

流行的例子

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- x^{2} = 1 - \frac{3 x ( x - 1 )}{2}

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x^{2} + 16 x = - 51

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