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受欢迎的代数 >

3x^2=19x-20

解答

3 x^{2} = 19 x - 20

解答

x = 5, x = \frac{4}{3}

+1

十进制

x = 5, x = 1.33333 \dots

求解步骤

3 x^{2} = 19 x - 20

将

20

para o lado esquerdo

3 x^{2} + 20 = 19 x

将

19 x

para o lado esquerdo

3 x^{2} + 20 - 19 x = 0

改写成标准形式

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

3 x^{2} - 19 x + 20 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 19 ) \pm ( - 19 ) ^{2} - 4 \cdot 3 \cdot 20}{2 \cdot 3}

(- 19)^{2} - 4 \cdot 3 \cdot 20 = 11

x_{1, 2} = \frac{- ( - 19 ) \pm 11}{2 \cdot 3}

将解分隔开

x_{1} = \frac{- ( - 19 ) + 11}{2 \cdot 3}, x_{2} = \frac{- ( - 19 ) - 11}{2 \cdot 3}

x = \frac{- ( - 19 ) + 11}{2 \cdot 3} : 5

x = \frac{- ( - 19 ) - 11}{2 \cdot 3} : \frac{4}{3}

二次方程组的解是:

x = 5, x = \frac{4}{3}

作图

流行的例子

(3+x) 2/m+6(3-x) 2/m =5(9-x^2) 1/m

(3 + x) \frac{2}{m} + 6 (3 - x) \frac{2}{m} = 5 (9 - x^{2}) \frac{1}{m}

(x + 3)^{2} - 81 = 0

x^{2} + 2 x + 2 + 8 = 0

x^{2} + 11 x - 80 = 0

- x^{2} - 14 = 8 x + 2