2x^2+2x-84=0

解

2 x^{2} + 2 x - 84 = 0

x = 6, x = - 7

解答ステップ

2 x^{2} + 2 x - 84 = 0

解くとthe二次式

x_{1, 2} = \frac{- 2 \pm 2 ^{2} - 4 \cdot 2 ( - 84 )}{2 \cdot 2}

2^{2} - 4 \cdot 2 (- 84) = 26

x_{1, 2} = \frac{- 2 \pm 26}{2 \cdot 2}

解を分離する

x_{1} = \frac{- 2 + 26}{2 \cdot 2}, x_{2} = \frac{- 2 - 26}{2 \cdot 2}

x = \frac{- 2 + 26}{2 \cdot 2} : 6

x = \frac{- 2 - 26}{2 \cdot 2} : - 7

二次equationの解:

x = 6, x = - 7