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受欢迎的代数 >

7x^2+21x-20=0

解答

7 x^{2} + 21 x - 20 = 0

解答

x = \frac{- 21 + 1001}{14}, x = \frac{- 21 - 1001}{14}

+1

十进制

x = 0.75989 \dots, x = - 3.75989 \dots

求解步骤

7 x^{2} + 21 x - 20 = 0

使用求根公式求解

x_{1, 2} = \frac{- 21 \pm 2 1 ^{2} - 4 \cdot 7 ( - 20 )}{2 \cdot 7}

2 1^{2} - 4 \cdot 7 (- 20) = 1001

x_{1, 2} = \frac{- 21 \pm 1001}{2 \cdot 7}

将解分隔开

x_{1} = \frac{- 21 + 1001}{2 \cdot 7}, x_{2} = \frac{- 21 - 1001}{2 \cdot 7}

x = \frac{- 21 + 1001}{2 \cdot 7} : \frac{- 21 + 1001}{14}

x = \frac{- 21 - 1001}{2 \cdot 7} : \frac{- 21 - 1001}{14}

二次方程组的解是:

x = \frac{- 21 + 1001}{14}, x = \frac{- 21 - 1001}{14}

作图

流行的例子

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