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受欢迎的代数 >

0.2x+3.1-2.1x=0.3x(x-5)+0.2

解答

0.2 x + 3.1 - 2.1 x = 0.3 x (x - 5) + 0.2

解答

x = \frac{- 2 + 91}{3}, x = - \frac{2 + 91}{3}

+1

十进制

x = 2.51313 \dots, x = - 3.84646 \dots

求解步骤

0.2 x + 3.1 - 2.1 x = 0.3 x (x - 5) + 0.2

在两边乘以

10

- 19 x + 31 = 3 x (x - 5) + 2

展开

3 x (x - 5) + 2 : 3 x^{2} - 15 x + 2

- 19 x + 31 = 3 x^{2} - 15 x + 2

交换两边

3 x^{2} - 15 x + 2 = - 19 x + 31

将

31

para o lado esquerdo

3 x^{2} - 15 x - 29 = - 19 x

将

19 x

para o lado esquerdo

3 x^{2} + 4 x - 29 = 0

使用求根公式求解

x_{1, 2} = \frac{- 4 \pm 4 ^{2} - 4 \cdot 3 ( - 29 )}{2 \cdot 3}

4^{2} - 4 \cdot 3 (- 29) = 291

x_{1, 2} = \frac{- 4 \pm 2 91}{2 \cdot 3}

将解分隔开

x_{1} = \frac{- 4 + 2 91}{2 \cdot 3}, x_{2} = \frac{- 4 - 2 91}{2 \cdot 3}

x = \frac{- 4 + 2 91}{2 \cdot 3} : \frac{- 2 + 91}{3}

x = \frac{- 4 - 2 91}{2 \cdot 3} : - \frac{2 + 91}{3}

二次方程组的解是:

x = \frac{- 2 + 91}{3}, x = - \frac{2 + 91}{3}

作图

流行的例子

(z^2)/6-z/2-45=0

\frac{z ^{2}}{6} - \frac{z}{2} - 45 = 0

m^{2} + 1.25 m = 0

3 t^{2} + 6 t = 0

completesquare s^2-12s+61

co m pl e t es q u a re s^{2} - 12 s + 61

8 x^{2} - 18 x = - 8