a = 5^14 (1+5^200+5^2000 )
b = 3^21 (1+3^300+3^3000 )
c = 2^35 (1+2^500 +2^5000 )
5^14 = (5²)^7 = 25^7 5^200 =( 5² )^100 = 25^100 5^2000 = 25^1000
3^21 = (3³ )^7 = 27^7 3^300 = (3³)^100 = 27^100 3^3000 = 27^1000
2^35 = (2^5 )^7 =32^7 2^500 = (2^5 )^100 = 32^100 2^5000 = 32^1000
⇒ a < b < c