Răspuns :
(49 supra 9) la puterea 21 : [(49 supra 9)la puterea 4] la puterea 5 =
= (49 supra 9) la 21 : (49 supra 9) la 20
= 49 supra 9 :)
= (49 supra 9) la 21 : (49 supra 9) la 20
= 49 supra 9 :)
(49/9)^21:5,(4)^20=49/9^21:{(54-5)/9}^20=(49/9)^(21-20)=(49/9)^1=49/9