Final answer:
The expression (3√7)² is solved by squaring 3 to get 9 and squaring √7 to get 7; then multiply these results to get 63.
Step-by-step explanation:
To solve how to square 3 times the square root of 7, we should analyze the expression algebraically. The expression can be written as (3√7)², which means we should square both 3 and the square root of 7 separately.
When we square 3, we get 9 (since 3² = 9), and when we square the square root of 7, we just get 7 (since (√7)² = 7). So, multiplying these together, we get 9 * 7 = 63.
Hence, the correct answer is 63, which is choice (b).