a^2+12a-85=0

解

a^{2} + 12 a - 85 = 0

a = 5, a = - 17

解答ステップ

a^{2} + 12 a - 85 = 0

解くとthe二次式

a_{1, 2} = \frac{- 12 \pm 1 2 ^{2} - 4 \cdot 1 \cdot ( - 85 )}{2 \cdot 1}

1 2^{2} - 4 \cdot 1 \cdot (- 85) = 22

a_{1, 2} = \frac{- 12 \pm 22}{2 \cdot 1}

解を分離する

a_{1} = \frac{- 12 + 22}{2 \cdot 1}, a_{2} = \frac{- 12 - 22}{2 \cdot 1}

a = \frac{- 12 + 22}{2 \cdot 1} : 5

a = \frac{- 12 - 22}{2 \cdot 1} : - 17

二次equationの解:

a = 5, a = - 17