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受欢迎的代数 >

x0.9(x+1)=25+x

解答

x 0.9 (x + 1) = 25 + x

解答

x = \frac{1 + 9001}{18}, x = \frac{1 - 9001}{18}

+1

十进制

x = 5.32631 \dots, x = - 5.21520 \dots

求解步骤

x \cdot 0.9 (x + 1) = 25 + x

在两边乘以

10

9 x (x + 1) = 250 + 10 x

展开

9 x (x + 1) : 9 x^{2} + 9 x

9 x^{2} + 9 x = 250 + 10 x

将

10 x

para o lado esquerdo

9 x^{2} - x = 250

将

250

para o lado esquerdo

9 x^{2} - x - 250 = 0

使用求根公式求解

x_{1, 2} = \frac{- ( - 1 ) \pm ( - 1 ) ^{2} - 4 \cdot 9 ( - 250 )}{2 \cdot 9}

(- 1)^{2} - 4 \cdot 9 (- 250) = 9001

x_{1, 2} = \frac{- ( - 1 ) \pm 9001}{2 \cdot 9}

将解分隔开

x_{1} = \frac{- ( - 1 ) + 9001}{2 \cdot 9}, x_{2} = \frac{- ( - 1 ) - 9001}{2 \cdot 9}

x = \frac{- ( - 1 ) + 9001}{2 \cdot 9} : \frac{1 + 9001}{18}

x = \frac{- ( - 1 ) - 9001}{2 \cdot 9} : \frac{1 - 9001}{18}

二次方程组的解是:

x = \frac{1 + 9001}{18}, x = \frac{1 - 9001}{18}

作图

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