a) a = 1 + 2⁰ + 2¹ +.....+2⁹⁸ =(2+ 2) + 2² +2³ + ............+2⁹⁸ =
= 2² + 2² + 2³ +.......+2⁹⁸ = 2³ + 2³ +.....+2⁹⁸ = 2⁹⁸ + 2⁹⁸ = 2⁹⁹
b = 2²⁰ ₓ2³⁶ₓ2¹² = 2⁶⁸ a> b
b) a = 3 + 2(3 + 3² + 3³ +.......+3⁸⁹)
S = 3 +3² + 3³ + .......+3⁸⁹
3S = 3² + 3³ +...........+3⁹⁰ 3S - S = 2S = 3⁹⁰ - 3 S = (3⁹⁰ - 3)/2
a = 3 + 2(3⁹⁰ - 3)/2 = 3 + 3⁹⁰ - 3 a = 3⁹⁰
b = 3¹⁴⁴ ⇒⇒ b > a