Answer:
square of the following
2×2=4
3×3=9
4×4=16
2×2×2=8
now
square root
√4
√2×2
=2 answer likewise other
again
cube root
√8
=√2×2×2
=2 through that you can find these
at first you should know square and cube of different numbers from 1 to 20 is the required you should know then you can easily find out answer