x^2-18x-40=0

解

x^{2} - 18 x - 40 = 0

x = 20, x = - 2

解答ステップ

x^{2} - 18 x - 40 = 0

解くとthe二次式

x_{1, 2} = \frac{- ( - 18 ) \pm ( - 18 ) ^{2} - 4 \cdot 1 \cdot ( - 40 )}{2 \cdot 1}

(- 18)^{2} - 4 \cdot 1 \cdot (- 40) = 22

x_{1, 2} = \frac{- ( - 18 ) \pm 22}{2 \cdot 1}

解を分離する

x_{1} = \frac{- ( - 18 ) + 22}{2 \cdot 1}, x_{2} = \frac{- ( - 18 ) - 22}{2 \cdot 1}

x = \frac{- ( - 18 ) + 22}{2 \cdot 1} : 20

x = \frac{- ( - 18 ) - 22}{2 \cdot 1} : - 2

二次equationの解:

x = 20, x = - 2