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受欢迎的代数 >

2x^2+7x=x^2+30

解答

2 x^{2} + 7 x = x^{2} + 30

解答

x = 3, x = - 10

求解步骤

2 x^{2} + 7 x = x^{2} + 30

将

30

para o lado esquerdo

2 x^{2} + 7 x - 30 = x^{2}

将

x^{2}

para o lado esquerdo

x^{2} + 7 x - 30 = 0

使用求根公式求解

x_{1, 2} = \frac{- 7 \pm 7 ^{2} - 4 \cdot 1 \cdot ( - 30 )}{2 \cdot 1}

7^{2} - 4 \cdot 1 \cdot (- 30) = 13

x_{1, 2} = \frac{- 7 \pm 13}{2 \cdot 1}

将解分隔开

x_{1} = \frac{- 7 + 13}{2 \cdot 1}, x_{2} = \frac{- 7 - 13}{2 \cdot 1}

x = \frac{- 7 + 13}{2 \cdot 1} : 3

x = \frac{- 7 - 13}{2 \cdot 1} : - 10

二次方程组的解是:

x = 3, x = - 10

作图

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