-4a^2-28a-40=0

解

- 4 a^{2} - 28 a - 40 = 0

a = - 5, a = - 2

解答ステップ

- 4 a^{2} - 28 a - 40 = 0

解くとthe二次式

a_{1, 2} = \frac{- ( - 28 ) \pm ( - 28 ) ^{2} - 4 ( - 4 ) ( - 40 )}{2 ( - 4 )}

(- 28)^{2} - 4 (- 4) (- 40) = 12

a_{1, 2} = \frac{- ( - 28 ) \pm 12}{2 ( - 4 )}

解を分離する

a_{1} = \frac{- ( - 28 ) + 12}{2 ( - 4 )}, a_{2} = \frac{- ( - 28 ) - 12}{2 ( - 4 )}

a = \frac{- ( - 28 ) + 12}{2 ( - 4 )} : - 5

a = \frac{- ( - 28 ) - 12}{2 ( - 4 )} : - 2

二次equationの解:

a = - 5, a = - 2