If 2^(1/3) < 3^(1/4), then

(2^(1/3))^3 < (3^(1/4))^3

2 < 3^(3/4)

2^4 < (3^(3/4))^4

16 < 3^3

16 < 27, which is true.

Therefore 2^(1/3) < 3^(1/4)

The actual proof requires you to start with 16 < 27 (which is a known true statement) and get to 2^(1/3) < 3^(1/4), but it's essentially the same, just going in reverse order.

Do the same for the other combinations of numbers you have been given.