v^2-v-20=0

解

v^{2} - v - 20 = 0

v = 5, v = - 4

解答ステップ

v^{2} - v - 20 = 0

解くとthe二次式

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

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

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

解を分離する

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

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

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

二次equationの解:

v = 5, v = - 4