4.9t^2-205.06t-210=0

解答

4.9 t^{2} - 205.06 t - 210 = 0

t = \frac{20506 + 461656036}{980}, t = \frac{20506 - 461656036}{980}

十进制

t = 42.84916 \dots, t = - 1.00018 \dots

求解步骤

4.9 t^{2} - 205.06 t - 210 = 0

在两边乘以

100

490 t^{2} - 20506 t - 21000 = 0

使用求根公式求解

t_{1, 2} = \frac{- ( - 20506 ) \pm ( - 20506 ) ^{2} - 4 \cdot 490 ( - 21000 )}{2 \cdot 490}

(- 20506)^{2} - 4 \cdot 490 (- 21000) = 461656036

t_{1, 2} = \frac{- ( - 20506 ) \pm 461656036}{2 \cdot 490}

将解分隔开

t_{1} = \frac{- ( - 20506 ) + 461656036}{2 \cdot 490}, t_{2} = \frac{- ( - 20506 ) - 461656036}{2 \cdot 490}

t = \frac{- ( - 20506 ) + 461656036}{2 \cdot 490} : \frac{20506 + 461656036}{980}

t = \frac{- ( - 20506 ) - 461656036}{2 \cdot 490} : \frac{20506 - 461656036}{980}

二次方程组的解是:

t = \frac{20506 + 461656036}{980}, t = \frac{20506 - 461656036}{980}

3 y^{2} - 20 y + 9 = - y^{2} + 8 y - 40

5 u (u + 2) + 5 = 0

(a x + b)^{2} - (b x + a)^{2} = 0

28 x^{2} - 21 x = 20 x - 15

(x - 2) (x + 4) = 5 x + 41