zs

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

受欢迎的代数 >

completesquare 2x^2-5x-2=0

解答

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

解答

x = \frac{41 + 5}{4}, x = \frac{- 41 + 5}{4}

+1

十进制

x = 2.85078 \dots, x = - 0.35078 \dots

求解步骤

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

将

2

到右边

2 x^{2} - 5 x = 2

两边除以

2

\frac{2 x ^{2} - 5 x}{2} = \frac{2}{2}

x^{2} - \frac{5 x}{2} = 1

改写为形式

(x + a)^{2} = b

(x - \frac{5}{4})^{2} = \frac{41}{16}

若

f^{2} (x) = a

，解为

f (x) = a, - a

解

x - \frac{5}{4} = \frac{41}{16} : x = \frac{41 + 5}{4}

解

x - \frac{5}{4} = - \frac{41}{16} : x = \frac{- 41 + 5}{4}

二次方程组的解是:

x = \frac{41 + 5}{4}, x = \frac{- 41 + 5}{4}

作图

流行的例子

4.905t^2-21t+12.5=0

4.905 t^{2} - 21 t + 12.5 = 0

x (x + 9) = 4 (x + 6)

9 x^{2} = - 12 x - 4

\frac{2 x + x ^{2}}{2} = 16

3 y^{2} - 7 y - 6 = 0