展开 (2(5+sqrt(10)))/5

解答

展开

\frac{2 ( 5 + 10 )}{5}

2 + \frac{2 2}{5}

十进制

3.26491 \dots

求解步骤

\frac{2 ( 5 + 10 )}{5}

乘开

2 (5 + 10) : 10 + 210

= \frac{10 + 2 10}{5}

使用分式法则:

\frac{a \pm b}{c} = \frac{a}{c} \pm \frac{b}{c}

\frac{10 + 2 10}{5} = \frac{10}{5} + \frac{2 10}{5}

= \frac{10}{5} + \frac{2 10}{5}

数字相除:

\frac{10}{5} = 2

= 2 + \frac{2 10}{5}

消掉

\frac{2 10}{5} : \frac{2 2}{5}

= 2 + \frac{2 2}{5}

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