k^2-k-56=0

解

k^{2} - k - 56 = 0

k = 8, k = - 7

解答ステップ

k^{2} - k - 56 = 0

解くとthe二次式

k_{1, 2} = \frac{- ( - 1 ) \pm ( - 1 ) ^{2} - 4 \cdot 1 \cdot ( - 56 )}{2 \cdot 1}

(- 1)^{2} - 4 \cdot 1 \cdot (- 56) = 15

k_{1, 2} = \frac{- ( - 1 ) \pm 15}{2 \cdot 1}

解を分離する

k_{1} = \frac{- ( - 1 ) + 15}{2 \cdot 1}, k_{2} = \frac{- ( - 1 ) - 15}{2 \cdot 1}

k = \frac{- ( - 1 ) + 15}{2 \cdot 1} : 8

k = \frac{- ( - 1 ) - 15}{2 \cdot 1} : - 7

二次equationの解:

k = 8, k = - 7