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受欢迎的代数 >

(14-2x)(20-2x)=108

解答

(14 - 2 x) (20 - 2 x) = 108

解答

x = \frac{17 + 3 13}{2}, x = \frac{17 - 3 13}{2}

+1

十进制

x = 13.90832 \dots, x = 3.09167 \dots

求解步骤

(14 - 2 x) (20 - 2 x) = 108

展开

(14 - 2 x) (20 - 2 x) : 280 - 68 x + 4 x^{2}

280 - 68 x + 4 x^{2} = 108

将

108

para o lado esquerdo

4 x^{2} - 68 x + 172 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 68 ) \pm ( - 68 ) ^{2} - 4 \cdot 4 \cdot 172}{2 \cdot 4}

(- 68)^{2} - 4 \cdot 4 \cdot 172 = 1213

x_{1, 2} = \frac{- ( - 68 ) \pm 12 13}{2 \cdot 4}

将解分隔开

x_{1} = \frac{- ( - 68 ) + 12 13}{2 \cdot 4}, x_{2} = \frac{- ( - 68 ) - 12 13}{2 \cdot 4}

x = \frac{- ( - 68 ) + 12 13}{2 \cdot 4} : \frac{17 + 3 13}{2}

x = \frac{- ( - 68 ) - 12 13}{2 \cdot 4} : \frac{17 - 3 13}{2}

二次方程组的解是:

x = \frac{17 + 3 13}{2}, x = \frac{17 - 3 13}{2}

作图

流行的例子

x^{2} + (7 - x) 2 = 30

x^{2} - 2 (x + 1) = 0

4 x^{2} - 4 x + 16 = 0

completesquare 3x^2+12x+7

co m pl e t es q u a re 3 x^{2} + 12 x + 7

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