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受欢迎的代数 >

(7x+2)^2+6(7x+2)=27

解答

(7 x + 2)^{2} + 6 (7 x + 2) = 27

解答

x = \frac{1}{7}, x = - \frac{11}{7}

+1

十进制

x = 0.14285 \dots, x = - 1.57142 \dots

求解步骤

(7 x + 2)^{2} + 6 (7 x + 2) = 27

展开

(7 x + 2)^{2} + 6 (7 x + 2) : 49 x^{2} + 70 x + 16

49 x^{2} + 70 x + 16 = 27

将

27

para o lado esquerdo

49 x^{2} + 70 x - 11 = 0

使用求根公式求解

x_{1, 2} = \frac{- 70 \pm 7 0 ^{2} - 4 \cdot 49 ( - 11 )}{2 \cdot 49}

7 0^{2} - 4 \cdot 49 (- 11) = 84

x_{1, 2} = \frac{- 70 \pm 84}{2 \cdot 49}

将解分隔开

x_{1} = \frac{- 70 + 84}{2 \cdot 49}, x_{2} = \frac{- 70 - 84}{2 \cdot 49}

x = \frac{- 70 + 84}{2 \cdot 49} : \frac{1}{7}

x = \frac{- 70 - 84}{2 \cdot 49} : - \frac{11}{7}

二次方程组的解是:

x = \frac{1}{7}, x = - \frac{11}{7}

作图

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