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受欢迎的代数 >

-5x^2+9+7x=0

解答

- 5 x^{2} + 9 + 7 x = 0

解答

x = - \frac{- 7 + 229}{10}, x = \frac{7 + 229}{10}

+1

十进制

x = - 0.81327 \dots, x = 2.21327 \dots

求解步骤

- 5 x^{2} + 9 + 7 x = 0

改写成标准形式

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

- 5 x^{2} + 7 x + 9 = 0

使用求根公式求解

x_{1, 2} = \frac{- 7 \pm 7 ^{2} - 4 ( - 5 ) \cdot 9}{2 ( - 5 )}

7^{2} - 4 (- 5) \cdot 9 = 229

x_{1, 2} = \frac{- 7 \pm 229}{2 ( - 5 )}

将解分隔开

x_{1} = \frac{- 7 + 229}{2 ( - 5 )}, x_{2} = \frac{- 7 - 229}{2 ( - 5 )}

x = \frac{- 7 + 229}{2 ( - 5 )} : - \frac{- 7 + 229}{10}

x = \frac{- 7 - 229}{2 ( - 5 )} : \frac{7 + 229}{10}

二次方程组的解是:

x = - \frac{- 7 + 229}{10}, x = \frac{7 + 229}{10}

作图

流行的例子

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25 x^{2} + 16 = 40 x