Question

$7 {}^{ - 1} - 21 {}^{ - 1}$
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Answer 1

Ответ:

$\frac{2}{21}$

Объяснение:

$7^{-1}-21^{-1}=\frac{1}{7}-\frac{1}{21} =\frac{3-1}{21}=\frac{2}{21}$

Answer 2

$7^{-1} -21^{-1} =\frac{1}{7} -\frac{1}{21} =\frac{1*3-1}{21} =\frac{3-1}{21} =\frac{2}{21}$