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受欢迎的代数 >

x*(20x-21)=27

解答

x \cdot (20 x - 21) = 27

解答

x = \frac{9}{5}, x = - \frac{3}{4}

+1

十进制

x = 1.8, x = - 0.75

求解步骤

x (20 x - 21) = 27

展开

x (20 x - 21) : 20 x^{2} - 21 x

20 x^{2} - 21 x = 27

将

27

para o lado esquerdo

20 x^{2} - 21 x - 27 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 21 ) \pm ( - 21 ) ^{2} - 4 \cdot 20 ( - 27 )}{2 \cdot 20}

(- 21)^{2} - 4 \cdot 20 (- 27) = 51

x_{1, 2} = \frac{- ( - 21 ) \pm 51}{2 \cdot 20}

将解分隔开

x_{1} = \frac{- ( - 21 ) + 51}{2 \cdot 20}, x_{2} = \frac{- ( - 21 ) - 51}{2 \cdot 20}

x = \frac{- ( - 21 ) + 51}{2 \cdot 20} : \frac{9}{5}

x = \frac{- ( - 21 ) - 51}{2 \cdot 20} : - \frac{3}{4}

二次方程组的解是:

x = \frac{9}{5}, x = - \frac{3}{4}

作图

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