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受欢迎的代数 >

x^2-1-2x=0

解答

x^{2} - 1 - 2 x = 0

解答

x = 1 + 2, x = 1 - 2

+1

十进制

x = 2.41421 \dots, x = - 0.41421 \dots

求解步骤

x^{2} - 1 - 2 x = 0

改写成标准形式

a x^{2} + b x + c = 0

x^{2} - 2 x - 1 = 0

使用求根公式求解

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

(- 2)^{2} - 4 \cdot 1 \cdot (- 1) = 22

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

将解分隔开

x_{1} = \frac{- ( - 2 ) + 2 2}{2 \cdot 1}, x_{2} = \frac{- ( - 2 ) - 2 2}{2 \cdot 1}

x = \frac{- ( - 2 ) + 2 2}{2 \cdot 1} : 1 + 2

x = \frac{- ( - 2 ) - 2 2}{2 \cdot 1} : 1 - 2

二次方程组的解是:

x = 1 + 2, x = 1 - 2

作图

流行的例子

198=0.1w^2+2.155w+20

198 = 0.1 w^{2} + 2.155 w + 20

solvefor x,-x^2-yx-0.05y=0

so l v e f or x, - x^{2} - y x - 0.05 y = 0

2k^2+3k^2+4k^2=116

2 k^{2} + 3 k^{2} + 4 k^{2} = 116

3q^2-112q+930=0

3 q^{2} - 112 q + 930 = 0

11.48=-0.5x^2+0.5x+15

11.48 = - 0.5 x^{2} + 0.5 x + 15