quadraticformula 7x^2+21x-28=0

解

7 x^{2} + 21 x - 28 = 0

x = 1, x = - 4

解答ステップ

7 x^{2} + 21 x - 28 = 0

解くとthe二次式

x_{1, 2} = \frac{- 21 \pm 2 1 ^{2} - 4 \cdot 7 ( - 28 )}{2 \cdot 7}

2 1^{2} - 4 \cdot 7 (- 28) = 35

x_{1, 2} = \frac{- 21 \pm 35}{2 \cdot 7}

解を分離する

x_{1} = \frac{- 21 + 35}{2 \cdot 7}, x_{2} = \frac{- 21 - 35}{2 \cdot 7}

x = \frac{- 21 + 35}{2 \cdot 7} : 1

x = \frac{- 21 - 35}{2 \cdot 7} : - 4

二次equationの解:

x = 1, x = - 4