a) 10 ^15= (2^5)^15 = 2^30
15^10 = (3^5)^10= 3^50
Vậy 10^15<15^10
b)16^19=(4^4)^19 =4^ 76
8^25=(2^3)^25 = 2^75
Vậy 16^19>8^25
c)49^8=(7^7)^8= 7^56
Vậy 49^8<21^15<27^5
d)1+2+2^3+2^4+...+2^9=3+2^2+2^3+...+2^9
=3+4+8+16+32+64+128+256+512=1023
5.2^8=5.256=1280