X^2-4X-5=0

解

X^{2} - 4 X - 5 = 0

X = 5, X = - 1

解答ステップ

X^{2} - 4 X - 5 = 0

解くとthe二次式

X_{1, 2} = \frac{- ( - 4 ) \pm ( - 4 ) ^{2} - 4 \cdot 1 \cdot ( - 5 )}{2 \cdot 1}

(- 4)^{2} - 4 \cdot 1 \cdot (- 5) = 6

X_{1, 2} = \frac{- ( - 4 ) \pm 6}{2 \cdot 1}

解を分離する

X_{1} = \frac{- ( - 4 ) + 6}{2 \cdot 1}, X_{2} = \frac{- ( - 4 ) - 6}{2 \cdot 1}

X = \frac{- ( - 4 ) + 6}{2 \cdot 1} : 5

X = \frac{- ( - 4 ) - 6}{2 \cdot 1} : - 1

二次equationの解:

X = 5, X = - 1