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受欢迎的代数 >

x^2-18x+78=0

解答

x^{2} - 18 x + 78 = 0

解答

x = 9 + 3, x = 9 - 3

+1

十进制

x = 10.73205 \dots, x = 7.26794 \dots

求解步骤

x^{2} - 18 x + 78 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 18 ) \pm ( - 18 ) ^{2} - 4 \cdot 1 \cdot 78}{2 \cdot 1}

(- 18)^{2} - 4 \cdot 1 \cdot 78 = 23

x_{1, 2} = \frac{- ( - 18 ) \pm 2 3}{2 \cdot 1}

将解分隔开

x_{1} = \frac{- ( - 18 ) + 2 3}{2 \cdot 1}, x_{2} = \frac{- ( - 18 ) - 2 3}{2 \cdot 1}

x = \frac{- ( - 18 ) + 2 3}{2 \cdot 1} : 9 + 3

x = \frac{- ( - 18 ) - 2 3}{2 \cdot 1} : 9 - 3

二次方程组的解是:

x = 9 + 3, x = 9 - 3

作图

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