The side length of a square is expanded three times, and its area is expanded () A. 3 times B. 6 times C. 9 times D. 12 times

The side length of a square is expanded three times, and its area is expanded () A. 3 times B. 6 times C. 9 times D. 12 times

(3a × 3a) / (a × a) = 92 △ A2 = 9 A: its area is expanded by 9 times