its the first option.
tiles of X and tiles of 1 are different
3 tiles of "X" = 3X
3 tiles of " 1 " = 3
option 3 does not mean 3X, it just means 3X + 3
Answer:

Step-by-step explanation:
1221 x 1221 = 1490841
square root of 1490841 is 1221
Answer:
5,114.6
Step-by-step explanation:
5.1146 x 10^3 means move decimal point 3 to the right to get the answer