k^2-9k+20=0

解

k^{2} - 9 k + 20 = 0

k = 5, k = 4

解答ステップ

k^{2} - 9 k + 20 = 0

解くとthe二次式

k_{1, 2} = \frac{- ( - 9 ) \pm ( - 9 ) ^{2} - 4 \cdot 1 \cdot 20}{2 \cdot 1}

(- 9)^{2} - 4 \cdot 1 \cdot 20 = 1

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

解を分離する

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

k = \frac{- ( - 9 ) + 1}{2 \cdot 1} : 5

k = \frac{- ( - 9 ) - 1}{2 \cdot 1} : 4

二次equationの解:

k = 5, k = 4