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受欢迎的代数 >

80+40t-4.9t^2=0

解答

80 + 40 t - 4.9 t^{2} = 0

解答

t = - \frac{20 ( 3 22 - 10 )}{49}, t = \frac{20 ( 10 + 3 22 )}{49}

+1

十进制

t = - 1.66173 \dots, t = 9.82499 \dots

求解步骤

80 + 40 t - 4.9 t^{2} = 0

在两边乘以

10

800 + 400 t - 49 t^{2} = 0

改写成标准形式

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

- 49 t^{2} + 400 t + 800 = 0

使用求根公式求解

t_{1, 2} = \frac{- 400 \pm 40 0 ^{2} - 4 ( - 49 ) \cdot 800}{2 ( - 49 )}

40 0^{2} - 4 (- 49) \cdot 800 = 12022

t_{1, 2} = \frac{- 400 \pm 120 22}{2 ( - 49 )}

将解分隔开

t_{1} = \frac{- 400 + 120 22}{2 ( - 49 )}, t_{2} = \frac{- 400 - 120 22}{2 ( - 49 )}

t = \frac{- 400 + 120 22}{2 ( - 49 )} : - \frac{20 ( 3 22 - 10 )}{49}

t = \frac{- 400 - 120 22}{2 ( - 49 )} : \frac{20 ( 10 + 3 22 )}{49}

二次方程组的解是:

t = - \frac{20 ( 3 22 - 10 )}{49}, t = \frac{20 ( 10 + 3 22 )}{49}

作图

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