Answer:
The answer is 1, 49x² & 81x⁶ is a perfect sq.
Explanation:
If you want to find which is perfect square, you can square root it :
√1 = 1
√24 ≠ whole no.
√66x ≠ whole no.
√49x² = 7x
√100x³ = 10x^... (100 is perfect sq. but x³ is not)
√81x⁶ = 9x³
When you sqrt. a no. , you get a whole no. which means it is a perfect sq.