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受欢迎的代数 >

(2x-7)^3=(2x)^3-7^3

解答

(2 x - 7)^{3} = (2 x)^{3} - 7^{3}

解答

x = 0, x = \frac{7}{2}

+1

十进制

x = 0, x = 3.5

求解步骤

(2 x - 7)^{3} = (2 x)^{3} - 7^{3}

展开

(2 x - 7)^{3} : 8 x^{3} - 84 x^{2} + 294 x - 343

展开

(2 x)^{3} - 7^{3} : 8 x^{3} - 343

8 x^{3} - 84 x^{2} + 294 x - 343 = 8 x^{3} - 343

将

343

para o lado esquerdo

8 x^{3} - 84 x^{2} + 294 x = 8 x^{3}

将

8 x^{3}

para o lado esquerdo

- 84 x^{2} + 294 x = 0

使用求根公式求解

x_{1, 2} = \frac{- 294 \pm 29 4 ^{2} - 4 ( - 84 ) \cdot 0}{2 ( - 84 )}

29 4^{2} - 4 (- 84) \cdot 0 = 294

x_{1, 2} = \frac{- 294 \pm 294}{2 ( - 84 )}

将解分隔开

x_{1} = \frac{- 294 + 294}{2 ( - 84 )}, x_{2} = \frac{- 294 - 294}{2 ( - 84 )}

x = \frac{- 294 + 294}{2 ( - 84 )} : 0

x = \frac{- 294 - 294}{2 ( - 84 )} : \frac{7}{2}

二次方程组的解是:

x = 0, x = \frac{7}{2}

作图

流行的例子

\frac{1}{2} x^{2} - 7 x + 7 = 0

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