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受欢迎的代数 >

2x=5-4x^2

解答

2 x = 5 - 4 x^{2}

解答

x = - \frac{1 + 21}{4}, x = \frac{21 - 1}{4}

+1

十进制

x = - 1.39564 \dots, x = 0.89564 \dots

求解步骤

2 x = 5 - 4 x^{2}

交换两边

5 - 4 x^{2} = 2 x

将

2 x

para o lado esquerdo

5 - 4 x^{2} - 2 x = 0

改写成标准形式

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

- 4 x^{2} - 2 x + 5 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 2 ) \pm ( - 2 ) ^{2} - 4 ( - 4 ) \cdot 5}{2 ( - 4 )}

(- 2)^{2} - 4 (- 4) \cdot 5 = 221

x_{1, 2} = \frac{- ( - 2 ) \pm 2 21}{2 ( - 4 )}

将解分隔开

x_{1} = \frac{- ( - 2 ) + 2 21}{2 ( - 4 )}, x_{2} = \frac{- ( - 2 ) - 2 21}{2 ( - 4 )}

x = \frac{- ( - 2 ) + 2 21}{2 ( - 4 )} : - \frac{1 + 21}{4}

x = \frac{- ( - 2 ) - 2 21}{2 ( - 4 )} : \frac{21 - 1}{4}

二次方程组的解是:

x = - \frac{1 + 21}{4}, x = \frac{21 - 1}{4}

作图

流行的例子

x - \frac{5}{2} < \frac{x}{4} - 6

2 - \frac{b}{3} = - \frac{5}{2}

化简 ((1/y+1/x))/(x/y-y/x)

s im pl i f y \frac{( \frac{1}{y} + \frac{1}{x} )}{\frac{x}{y} - \frac{y}{x}}

化简-n+(-4)-(-4n)+6

s im pl i f y - n + (- 4) - (- 4 n) + 6

2(3x+3)-4(5x-3)=x(x-3)-x(x+5)

2 (3 x + 3) - 4 (5 x - 3) = x (x - 3) - x (x + 5)