simple trigonometry

[arcticknock]

Hi guys,
I'm having some troubles with this problem:
If SINxCOSx=1/5, then SIN^4x + COS^4x is equal to?

 

[wjm11]

Hi guys,
I'm having some troubles with this problem:
If SINxCOSx=1/5, then SIN^4x + COS^4x is equal to?

Hint/Some things that may help:

(a^2 + b^2)^2 = a^4 + b^4 + 2(ab)^2