b^2-8b-20=0

解

b^{2} - 8 b - 20 = 0

b = 10, b = - 2

解答ステップ

b^{2} - 8 b - 20 = 0

解くとthe二次式

b_{1, 2} = \frac{- ( - 8 ) \pm ( - 8 ) ^{2} - 4 \cdot 1 \cdot ( - 20 )}{2 \cdot 1}

(- 8)^{2} - 4 \cdot 1 \cdot (- 20) = 12

b_{1, 2} = \frac{- ( - 8 ) \pm 12}{2 \cdot 1}

解を分離する

b_{1} = \frac{- ( - 8 ) + 12}{2 \cdot 1}, b_{2} = \frac{- ( - 8 ) - 12}{2 \cdot 1}

b = \frac{- ( - 8 ) + 12}{2 \cdot 1} : 10

b = \frac{- ( - 8 ) - 12}{2 \cdot 1} : - 2

二次equationの解:

b = 10, b = - 2