40(x+3)-3x(x+3)=40x

解答

40 (x + 3) - 3 x (x + 3) = 40 x

x = - 8, x = 5

求解步骤

40 (x + 3) - 3 x (x + 3) = 40 x

展开

40 (x + 3) - 3 x (x + 3) : - 3 x^{2} + 31 x + 120

- 3 x^{2} + 31 x + 120 = 40 x

将

40 x

para o lado esquerdo

- 3 x^{2} - 9 x + 120 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 9 ) \pm ( - 9 ) ^{2} - 4 ( - 3 ) \cdot 120}{2 ( - 3 )}

(- 9)^{2} - 4 (- 3) \cdot 120 = 39

x_{1, 2} = \frac{- ( - 9 ) \pm 39}{2 ( - 3 )}

将解分隔开

x_{1} = \frac{- ( - 9 ) + 39}{2 ( - 3 )}, x_{2} = \frac{- ( - 9 ) - 39}{2 ( - 3 )}

x = \frac{- ( - 9 ) + 39}{2 ( - 3 )} : - 8

x = \frac{- ( - 9 ) - 39}{2 ( - 3 )} : 5

二次方程组的解是:

x = - 8, x = 5

- 8 x + 14 \geq 60 or - 4 x + 50 < 58

2 (x - 2) + 3 x < 5 x + 6

0.06 = (0.000001) (256) (256 - x)

9 (\frac{x}{3} - 6 x) + 8 = - (- 2 x + 5)

2 \cdot \frac{5}{4}