-3x^2+21x=0

解

- 3 x^{2} + 21 x = 0

x = 0, x = 7

解答ステップ

- 3 x^{2} + 21 x = 0

解くとthe二次式

x_{1, 2} = \frac{- 21 \pm 2 1 ^{2} - 4 ( - 3 ) \cdot 0}{2 ( - 3 )}

2 1^{2} - 4 (- 3) \cdot 0 = 21

x_{1, 2} = \frac{- 21 \pm 21}{2 ( - 3 )}

解を分離する

x_{1} = \frac{- 21 + 21}{2 ( - 3 )}, x_{2} = \frac{- 21 - 21}{2 ( - 3 )}

x = \frac{- 21 + 21}{2 ( - 3 )} : 0

x = \frac{- 21 - 21}{2 ( - 3 )} : 7

二次equationの解:

x = 0, x = 7