81x^2+90x+25=0

解

81 x^{2} + 90 x + 25 = 0

x = - \frac{5}{9}

十進法表記

x = - 0.55555 \dots

解答ステップ

81 x^{2} + 90 x + 25 = 0

解くとthe二次式

x_{1, 2} = \frac{- 90 \pm 9 0 ^{2} - 4 \cdot 81 \cdot 25}{2 \cdot 81}

9 0^{2} - 4 \cdot 81 \cdot 25 = 0

x_{1, 2} = \frac{- 90 \pm 0}{2 \cdot 81}

x = \frac{- 90}{2 \cdot 81}

\frac{- 90}{2 \cdot 81} = - \frac{5}{9}

x = - \frac{5}{9}

二次equationの解:

x = - \frac{5}{9}