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受欢迎的代数 >

-4x^2+8x+7=0

解答

- 4 x^{2} + 8 x + 7 = 0

解答

x = - \frac{- 2 + 11}{2}, x = \frac{2 + 11}{2}

+1

十进制

x = - 0.65831 \dots, x = 2.65831 \dots

求解步骤

- 4 x^{2} + 8 x + 7 = 0

使用求根公式求解

x_{1, 2} = \frac{- 8 \pm 8 ^{2} - 4 ( - 4 ) \cdot 7}{2 ( - 4 )}

8^{2} - 4 (- 4) \cdot 7 = 411

x_{1, 2} = \frac{- 8 \pm 4 11}{2 ( - 4 )}

将解分隔开

x_{1} = \frac{- 8 + 4 11}{2 ( - 4 )}, x_{2} = \frac{- 8 - 4 11}{2 ( - 4 )}

x = \frac{- 8 + 4 11}{2 ( - 4 )} : - \frac{- 2 + 11}{2}

x = \frac{- 8 - 4 11}{2 ( - 4 )} : \frac{2 + 11}{2}

二次方程组的解是:

x = - \frac{- 2 + 11}{2}, x = \frac{2 + 11}{2}

作图

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