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受欢迎的代数 >

x^2-(2x-21)^2=144

解答

x^{2} - (2 x - 21)^{2} = 144

解答

x = 13, x = 15

求解步骤

x^{2} - (2 x - 21)^{2} = 144

展开

x^{2} - (2 x - 21)^{2} : - 3 x^{2} + 84 x - 441

- 3 x^{2} + 84 x - 441 = 144

将

144

para o lado esquerdo

- 3 x^{2} + 84 x - 585 = 0

使用求根公式求解

x_{1, 2} = \frac{- 84 \pm 8 4 ^{2} - 4 ( - 3 ) ( - 585 )}{2 ( - 3 )}

8 4^{2} - 4 (- 3) (- 585) = 6

x_{1, 2} = \frac{- 84 \pm 6}{2 ( - 3 )}

将解分隔开

x_{1} = \frac{- 84 + 6}{2 ( - 3 )}, x_{2} = \frac{- 84 - 6}{2 ( - 3 )}

x = \frac{- 84 + 6}{2 ( - 3 )} : 13

x = \frac{- 84 - 6}{2 ( - 3 )} : 15

二次方程组的解是:

x = 13, x = 15

作图

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