a) 2^91=(2^13)^7=8192^7
5^35=(5^5)^7=3125^7
Mà 8192>3125=>8192^7>3125^7
=>2^91>5^35
b) 107^50 < 108^50 = (4.27)^50 = (2^2.3^3)^50 = 2^100.3^150
73^75 > 72^75 = (8.9)^75 = (2^3.3^2)^75 = 2^225.3^150
Mà 107^50 < 108^50 = 2^100.3^150 < 2^225.3^150 = 72^75 < 73^75
=> 107^50 < 73^75
b,10750=(1072)25=1144925
7375=(733)25=38901725
38901725>1144925 =>10750<73757
vậy 10750<7375
a,291=(213)7=81927
535=(55)7=31257
81927>31257 =>291>535
vậy 291>535