r^2-r-30=0

解

r^{2} - r - 30 = 0

r = 6, r = - 5

解答ステップ

r^{2} - r - 30 = 0

解くとthe二次式

r_{1, 2} = \frac{- ( - 1 ) \pm ( - 1 ) ^{2} - 4 \cdot 1 \cdot ( - 30 )}{2 \cdot 1}

(- 1)^{2} - 4 \cdot 1 \cdot (- 30) = 11

r_{1, 2} = \frac{- ( - 1 ) \pm 11}{2 \cdot 1}

解を分離する

r_{1} = \frac{- ( - 1 ) + 11}{2 \cdot 1}, r_{2} = \frac{- ( - 1 ) - 11}{2 \cdot 1}

r = \frac{- ( - 1 ) + 11}{2 \cdot 1} : 6

r = \frac{- ( - 1 ) - 11}{2 \cdot 1} : - 5

二次equationの解:

r = 6, r = - 5