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受欢迎的代数 >

x^2+18x+81=25+81

解答

x^{2} + 18 x + 81 = 25 + 81

解答

x = - 9 + 106, x = - 9 - 106

+1

十进制

x = 1.29563 \dots, x = - 19.29563 \dots

求解步骤

x^{2} + 18 x + 81 = 25 + 81

整理后得

x^{2} + 18 x + 81 = 106

将

106

para o lado esquerdo

x^{2} + 18 x - 25 = 0

使用求根公式求解

x_{1, 2} = \frac{- 18 \pm 1 8 ^{2} - 4 \cdot 1 \cdot ( - 25 )}{2 \cdot 1}

1 8^{2} - 4 \cdot 1 \cdot (- 25) = 2106

x_{1, 2} = \frac{- 18 \pm 2 106}{2 \cdot 1}

将解分隔开

x_{1} = \frac{- 18 + 2 106}{2 \cdot 1}, x_{2} = \frac{- 18 - 2 106}{2 \cdot 1}

x = \frac{- 18 + 2 106}{2 \cdot 1} : - 9 + 106

x = \frac{- 18 - 2 106}{2 \cdot 1} : - 9 - 106

二次方程组的解是:

x = - 9 + 106, x = - 9 - 106

作图

流行的例子

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x (x - 9) = - 14

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100 = 0.89 x^{2} - 0.181 x - 0.338

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