y=loga(ab)+logb(ba)=loga−logbloga+logb−logalogb=2−(logab+logba)
[∵logxy=logx−logy&logab=logbloga]
Now using, A.M.≥G.M
logab+logba≥2√logablogba=2
⇒2−(logab+logba)≤0
Ans: 0