Question

Вычислить (7^-1-21^-1)

Answer 1

Ответ:   $\frac{2}{21}$ .

Объяснение:

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

Answer 2

To compute the expression (7^-1 - 21^-1), we need to find the reciprocals of 7 and 21 and then subtract them.

Reciprocal of a number 'x' is simply 1/x.

So, (7^-1) = 1/7 and (21^-1) = 1/21.

Now, we can substitute these values into the expression:

(7^-1 - 21^-1) = (1/7 - 1/21)

To subtract fractions, we need a common denominator, which in this case is 21:

(1/7 - 1/21) = (3/21 - 1/21)

Now, we can subtract the fractions with the same denominator:

(3/21 - 1/21) = 2/21

Therefore, (7^-1 - 21^-1) is equal to 2/21.