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受欢迎的代数 >

c(x)=0.3x^2+1.2x+4

解答

c (x) = 0.3 x^{2} + 1.2 x + 4

解答

x = \frac{- 6 + 5 c + 25 c ^{2} - 60 c - 84}{3}, x = \frac{- 6 + 5 c - 25 c ^{2} - 60 c - 84}{3}

求解步骤

c (x) = 0.3 x^{2} + 1.2 x + 4

在两边乘以

10

c x \cdot 10 = 3 x^{2} + 12 x + 40

交换两边

3 x^{2} + 12 x + 40 = c x \cdot 10

将

c x 10

para o lado esquerdo

3 x^{2} + 12 x + 40 - c x \cdot 10 = 0

改写成标准形式

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

3 x^{2} + (12 - c \cdot 10) x + 40 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( 12 - c \cdot 10 ) \pm ( 12 - c \cdot 10 ) ^{2} - 4 \cdot 3 \cdot 40}{2 \cdot 3}

化简

(12 - c \cdot 10)^{2} - 4 \cdot 3 \cdot 40 : 2 25 c^{2} - 60 c - 84

x_{1, 2} = \frac{- ( 12 - c \cdot 10 ) \pm 2 25 c ^{2} - 60 c - 84}{2 \cdot 3}

将解分隔开

x_{1} = \frac{- ( 12 - c \cdot 10 ) + 2 25 c ^{2} - 60 c - 84}{2 \cdot 3}, x_{2} = \frac{- ( 12 - c \cdot 10 ) - 2 25 c ^{2} - 60 c - 84}{2 \cdot 3}

x = \frac{- ( 12 - c 10 ) + 2 25 c ^{2} - 60 c - 84}{2 \cdot 3} : \frac{- 6 + 5 c + 25 c ^{2} - 60 c - 84}{3}

x = \frac{- ( 12 - c 10 ) - 2 25 c ^{2} - 60 c - 84}{2 \cdot 3} : \frac{- 6 + 5 c - 25 c ^{2} - 60 c - 84}{3}

二次方程组的解是:

x = \frac{- 6 + 5 c + 25 c ^{2} - 60 c - 84}{3}, x = \frac{- 6 + 5 c - 25 c ^{2} - 60 c - 84}{3}

作图

流行的例子

solvefor x,x^2-yx+y^2=7

so l v e f or x, x^{2} - y x + y^{2} = 7

solvefor y,f=x^2-x^3y^2

so l v e f or y, f = x^{2} - x^{3} y^{2}

x^2-61x^2+900=0

x^{2} - 61 x^{2} + 900 = 0

0 = x^{2} - 2 x - 35

x^{2} + 15 = 10 x