x^2+20x+91=0

解

x^{2} + 20 x + 91 = 0

x = - 7, x = - 13

解答ステップ

x^{2} + 20 x + 91 = 0

解くとthe二次式

x_{1, 2} = \frac{- 20 \pm 2 0 ^{2} - 4 \cdot 1 \cdot 91}{2 \cdot 1}

2 0^{2} - 4 \cdot 1 \cdot 91 = 6

x_{1, 2} = \frac{- 20 \pm 6}{2 \cdot 1}

解を分離する

x_{1} = \frac{- 20 + 6}{2 \cdot 1}, x_{2} = \frac{- 20 - 6}{2 \cdot 1}

x = \frac{- 20 + 6}{2 \cdot 1} : - 7

x = \frac{- 20 - 6}{2 \cdot 1} : - 13

二次equationの解:

x = - 7, x = - 13