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受欢迎的代数 >

-20/3 =10x-5x^2

解答

- \frac{20}{3} = 10 x - 5 x^{2}

解答

x = - \frac{- 3 + 21}{3}, x = \frac{3 + 21}{3}

+1

十进制

x = - 0.52752 \dots, x = 2.52752 \dots

求解步骤

- \frac{20}{3} = 10 x - 5 x^{2}

在两边乘以

3

- 20 = 30 x - 15 x^{2}

交换两边

30 x - 15 x^{2} = - 20

将

20

para o lado esquerdo

30 x - 15 x^{2} + 20 = 0

改写成标准形式

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

- 15 x^{2} + 30 x + 20 = 0

使用求根公式求解

x_{1, 2} = \frac{- 30 \pm 3 0 ^{2} - 4 ( - 15 ) \cdot 20}{2 ( - 15 )}

3 0^{2} - 4 (- 15) \cdot 20 = 1021

x_{1, 2} = \frac{- 30 \pm 10 21}{2 ( - 15 )}

将解分隔开

x_{1} = \frac{- 30 + 10 21}{2 ( - 15 )}, x_{2} = \frac{- 30 - 10 21}{2 ( - 15 )}

x = \frac{- 30 + 10 21}{2 ( - 15 )} : - \frac{- 3 + 21}{3}

x = \frac{- 30 - 10 21}{2 ( - 15 )} : \frac{3 + 21}{3}

二次方程组的解是:

x = - \frac{- 3 + 21}{3}, x = \frac{3 + 21}{3}

作图

流行的例子

y^{2} + 28 y - 27 = 0

x+7>15\land-3x+4>= 7

x + 7 > 15 and - 3 x + 4 \geq 7

s im pl i f y 2^{1.5}

3 x^{2} - 5 x = 12

∣ x - 2 ∣ - 2 = 4