solvefor x,x^2+7x-2=0

解答

x, x^{2} + 7 x - 2 = 0

x = \frac{- 7 + 57}{2}, x = \frac{- 7 - 57}{2}

十进制

x = 0.27491 \dots, x = - 7.27491 \dots

求解步骤

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

使用求根公式求解

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

7^{2} - 4 \cdot 1 \cdot (- 2) = 57

x_{1, 2} = \frac{- 7 \pm 57}{2 \cdot 1}

将解分隔开

x_{1} = \frac{- 7 + 57}{2 \cdot 1}, x_{2} = \frac{- 7 - 57}{2 \cdot 1}

x = \frac{- 7 + 57}{2 \cdot 1} : \frac{- 7 + 57}{2}

x = \frac{- 7 - 57}{2 \cdot 1} : \frac{- 7 - 57}{2}

二次方程组的解是:

x = \frac{- 7 + 57}{2}, x = \frac{- 7 - 57}{2}

x^{2} + 5 x - 6.25 = 43.75

x^{2} + 83 = - 20 x

x^{2} - 0.016 x - 0.064 = 0

so l v e f or x, x y - x^{2} + 3 = 0

15 y^{2} - 4 y - 4 = 0