9^20 > 27^13 ( t...i...c...k n...h...a )
920 > 2713 t....i.....c....k n....h.....a !!!
920=(32)20=340(1)
2713=(33)13=339(2)
từ (1);(2)
=>340>339=>920>2713
Ta có: 920=(32)20=340
2713=(33)13=339
Ta thấy: 40>39 =>340>339 hay 920>2713
Vậy 920>2713
Ta có:
920=(32)20=340
2713=(33)13=339
Mà 339<340
Suy ra: 2713 <920