x^2-7x-8=0

解

x^{2} - 7 x - 8 = 0

x = 8, x = - 1

解答ステップ

x^{2} - 7 x - 8 = 0

解くとthe二次式

x_{1, 2} = \frac{- ( - 7 ) \pm ( - 7 ) ^{2} - 4 \cdot 1 \cdot ( - 8 )}{2 \cdot 1}

(- 7)^{2} - 4 \cdot 1 \cdot (- 8) = 9

x_{1, 2} = \frac{- ( - 7 ) \pm 9}{2 \cdot 1}

解を分離する

x_{1} = \frac{- ( - 7 ) + 9}{2 \cdot 1}, x_{2} = \frac{- ( - 7 ) - 9}{2 \cdot 1}

x = \frac{- ( - 7 ) + 9}{2 \cdot 1} : 8

x = \frac{- ( - 7 ) - 9}{2 \cdot 1} : - 1

二次equationの解:

x = 8, x = - 1