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受欢迎的代数 >

0=40+5x-4.9x^2

解答

0 = 40 + 5 x - 4.9 x^{2}

解答

x = - \frac{5 ( 809 - 5 )}{49}, x = \frac{5 ( 5 + 809 )}{49}

+1

十进制

x = - 2.39213 \dots, x = 3.41254 \dots

求解步骤

0 = 40 + 5 x - 4.9 x^{2}

在两边乘以

10

0 = 400 + 50 x - 49 x^{2}

交换两边

400 + 50 x - 49 x^{2} = 0

改写成标准形式

a x^{2} + b x + c = 0

- 49 x^{2} + 50 x + 400 = 0

使用求根公式求解

x_{1, 2} = \frac{- 50 \pm 5 0 ^{2} - 4 ( - 49 ) \cdot 400}{2 ( - 49 )}

5 0^{2} - 4 (- 49) \cdot 400 = 10809

x_{1, 2} = \frac{- 50 \pm 10 809}{2 ( - 49 )}

将解分隔开

x_{1} = \frac{- 50 + 10 809}{2 ( - 49 )}, x_{2} = \frac{- 50 - 10 809}{2 ( - 49 )}

x = \frac{- 50 + 10 809}{2 ( - 49 )} : - \frac{5 ( 809 - 5 )}{49}

x = \frac{- 50 - 10 809}{2 ( - 49 )} : \frac{5 ( 5 + 809 )}{49}

二次方程组的解是:

x = - \frac{5 ( 809 - 5 )}{49}, x = \frac{5 ( 5 + 809 )}{49}

作图

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