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受欢迎的代数 >

c=200-7x+0.345x^2

解答

c = 200 - 7 x + 0.345 x^{2}

解答

x = \frac{7000 + 1380000 c - 227000000}{690}, x = \frac{7000 - 1380000 c - 227000000}{690}

求解步骤

c = 200 - 7 x + 0.345 x^{2}

在两边乘以

1000

c \cdot 1000 = 200000 - 7000 x + 345 x^{2}

交换两边

200000 - 7000 x + 345 x^{2} = c \cdot 1000

将

c 1000

para o lado esquerdo

200000 - 7000 x + 345 x^{2} - c \cdot 1000 = 0

改写成标准形式

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

345 x^{2} - 7000 x + 200000 - c \cdot 1000 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 7000 ) \pm ( - 7000 ) ^{2} - 4 \cdot 345 ( 200000 - c \cdot 1000 )}{2 \cdot 345}

化简

(- 7000)^{2} - 4 \cdot 345 (200000 - c \cdot 1000) : 1380000 c - 227000000

x_{1, 2} = \frac{- ( - 7000 ) \pm 1380000 c - 227000000}{2 \cdot 345}

将解分隔开

x_{1} = \frac{- ( - 7000 ) + 1380000 c - 227000000}{2 \cdot 345}, x_{2} = \frac{- ( - 7000 ) - 1380000 c - 227000000}{2 \cdot 345}

x = \frac{- ( - 7000 ) + 1380000 c - 227000000}{2 \cdot 345} : \frac{7000 + 1380000 c - 227000000}{690}

x = \frac{- ( - 7000 ) - 1380000 c - 227000000}{2 \cdot 345} : \frac{7000 - 1380000 c - 227000000}{690}

二次方程组的解是:

x = \frac{7000 + 1380000 c - 227000000}{690}, x = \frac{7000 - 1380000 c - 227000000}{690}

作图

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