t^2-7t-18=0

解

t^{2} - 7 t - 18 = 0

t = 9, t = - 2

解答ステップ

t^{2} - 7 t - 18 = 0

解くとthe二次式

t_{1, 2} = \frac{- ( - 7 ) \pm ( - 7 ) ^{2} - 4 \cdot 1 \cdot ( - 18 )}{2 \cdot 1}

(- 7)^{2} - 4 \cdot 1 \cdot (- 18) = 11

t_{1, 2} = \frac{- ( - 7 ) \pm 11}{2 \cdot 1}

解を分離する

t_{1} = \frac{- ( - 7 ) + 11}{2 \cdot 1}, t_{2} = \frac{- ( - 7 ) - 11}{2 \cdot 1}

t = \frac{- ( - 7 ) + 11}{2 \cdot 1} : 9

t = \frac{- ( - 7 ) - 11}{2 \cdot 1} : - 2

二次equationの解:

t = 9, t = - 2