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受欢迎的代数 >

-7x^2+4x+2/5 =0

解答

- 7 x^{2} + 4 x + \frac{2}{5} = 0

解答

x = - \frac{- 10 + 170}{35}, x = \frac{10 + 170}{35}

+1

十进制

x = - 0.08681 \dots, x = 0.65824 \dots

求解步骤

- 7 x^{2} + 4 x + \frac{2}{5} = 0

在两边乘以

5

- 35 x^{2} + 20 x + 2 = 0

使用求根公式求解

x_{1, 2} = \frac{- 20 \pm 2 0 ^{2} - 4 ( - 35 ) \cdot 2}{2 ( - 35 )}

2 0^{2} - 4 (- 35) \cdot 2 = 2170

x_{1, 2} = \frac{- 20 \pm 2 170}{2 ( - 35 )}

将解分隔开

x_{1} = \frac{- 20 + 2 170}{2 ( - 35 )}, x_{2} = \frac{- 20 - 2 170}{2 ( - 35 )}

x = \frac{- 20 + 2 170}{2 ( - 35 )} : - \frac{- 10 + 170}{35}

x = \frac{- 20 - 2 170}{2 ( - 35 )} : \frac{10 + 170}{35}

二次方程组的解是:

x = - \frac{- 10 + 170}{35}, x = \frac{10 + 170}{35}

作图

流行的例子

(x - 2)^{2} - 72 = 0

x^{2} = 5 (x + 210)

solvefor x,g(1-t)=3x^2-5x+1

so l v e f or x, g (1 - t) = 3 x^{2} - 5 x + 1

6 a^{2} + 31 a + 5 = 0

2 p^{2} + 3 p - 4 = 0