u^2+10u+21=0

解

u^{2} + 10 u + 21 = 0

u = - 3, u = - 7

解答ステップ

u^{2} + 10 u + 21 = 0

解くとthe二次式

u_{1, 2} = \frac{- 10 \pm 1 0 ^{2} - 4 \cdot 1 \cdot 21}{2 \cdot 1}

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

u_{1, 2} = \frac{- 10 \pm 4}{2 \cdot 1}

解を分離する

u_{1} = \frac{- 10 + 4}{2 \cdot 1}, u_{2} = \frac{- 10 - 4}{2 \cdot 1}

u = \frac{- 10 + 4}{2 \cdot 1} : - 3

u = \frac{- 10 - 4}{2 \cdot 1} : - 7

二次equationの解:

u = - 3, u = - 7