@ (A,B) = average of A and B
*(A,B) = product of A and B
/(A,B) = A divided by B
Which expression gives the sum of A and B?
First, let's break down the operations defined in the question:
We need to find an expression for the sum of A and B.
Consider the expression *(@(A, B), 2).
1. Calculate the average of A and B using @(A, B):
\[\text{@}(A, B) = \frac{A+B}{2}\]
2. Multiply the result by 2 using the * function:
\[*\left(\frac{A+B}{2}, 2\right) = \frac{A+B}{2} \times 2 = A + B\]
Thus, the expression *(@(A, B), 2) indeed gives the sum of A and B.
For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: