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受欢迎的代数 >

50=-0.5x^2+40x-300

解答

50 = - 0.5 x^{2} + 40 x - 300

解答

x = 10, x = 70

求解步骤

50 = - 0.5 x^{2} + 40 x - 300

在两边乘以

10

500 = - 5 x^{2} + 400 x - 3000

交换两边

- 5 x^{2} + 400 x - 3000 = 500

将

500

para o lado esquerdo

- 5 x^{2} + 400 x - 3500 = 0

使用求根公式求解

x_{1, 2} = \frac{- 400 \pm 40 0 ^{2} - 4 ( - 5 ) ( - 3500 )}{2 ( - 5 )}

40 0^{2} - 4 (- 5) (- 3500) = 300

x_{1, 2} = \frac{- 400 \pm 300}{2 ( - 5 )}

将解分隔开

x_{1} = \frac{- 400 + 300}{2 ( - 5 )}, x_{2} = \frac{- 400 - 300}{2 ( - 5 )}

x = \frac{- 400 + 300}{2 ( - 5 )} : 10

x = \frac{- 400 - 300}{2 ( - 5 )} : 70

二次方程组的解是:

x = 10, x = 70

作图

流行的例子

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2 x + x^{2} = - 13

10 x^{2} + 25 x = 15

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