What can come in place of the question mark (?) in the following expression?…

Concept: For any positive base with exponents m and n, the power-of-a-power rule states (am)n = am×n. A fractional exponent represents a root: a1/2 means the square root of a.

1. The expression is (71/2)2 — base 7, inner exponent 1/2, outer exponent 2.

2. Apply the power-of-a-power rule: (71/2)2 = 71/2 × 2.

3. Multiply the exponents: 1/2 × 2 = 1, so the expression becomes 71.

4. 71 = 7.

Cross-check: since 71/2 = √7, squaring √7 directly returns 7 (squaring undoes a square root). Also, 7 can be written as 491/2, because √49 = 7.

So (71/2)2 = 7 = 491/2.