L1 is regular as w<=5 lets means its bounded so lets take it epslone for eg and remaning x we can take {a,b} therefore language be (a+b)* which is regular.
L2 its like{ a* U b* U a^n b^n | n>=0} its not regular ..at first look i thought it may be a*b* but it cannot produce abb,aabbb,aaab means a's and b's are dependent so its not regular.
L3=a^2n| n is even positive number lets take n=0 ,2,4,6,8,10.....then L3={epslone,aaaa,aaaaaaaa,aaaaaaaaaaaa.....} its in AP mode so this is also regular
