Question

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Answer 1

$(\frac{r}{4} + \frac{r}{5} ) * \frac{1}{r^{2} } = \frac{9}{20} r * \frac{1}{r^{2} } = \frac{9}{20} * \frac{1}{r} = \frac{9}{20r}$

Answer 2

Ответ:

$\frac{9}{20r}$

Объяснение:

$( \frac{r}{4} + \frac{r}{5} ) \times \frac{1}{r {}^{2} } =\frac{9}{20}r\times \left(\frac{1}{r^{2}}\right) =\frac{9}{20r^{2}}r =\frac{9r}{20r^{2}} =\frac{9}{20r}$