All of them are true.

When you see this kind of problem make sure what is asked could or must be true.
if it is Must then try to prove one case where the concerned sentence will be wrong.
if it is Could then try to prove one case where the concerned sentence will be correct.

There is no simpler method than putting random values with an intelligent guess

1. x>y>z: any positive integers can be taken to prove so.
Say x = 16 y=2 and z =1

2. z>y>x: clue here is you have to take fractions here. say x=1/4 y=1/3 z = 1/2

3. x>z>y: as x will be greater than others z and y. so take x =1 y=1/3 z = 1/2

When see a could be kind of question try to manipulate the options with values like 0,1 and fractions

For problems like this, I usually test cases.

taneja.niks wrote:If x>y^2>z^4 which of the following could be true??

1) x>y>z
2) Z>y>x
3) X>z>y


Please explain how to approach such questions

Could be true -- any one set of data would suffice.

Plugging in different values for x, y and z would be sufficient to solve this problem.

Answer would be all of the above.