Tính:
a. [5^19.3 + 5^19.4] : 5^19
= 5^19(3 + 4) : 5^19
= 5^19.7 : 5^19
= 7
b.[3^15.4+5.3^15] : 3^16
= 3^15(4 + 3) : 3^16
= 3^15.7 : 3^16
= 7/3
c. [2^13.7+2^13.9] : 2^16
= 2^13(7 + 13) : 2^16
= 2^13.20 : 2^16
= 5/2
d. [7^13.5+11.7^14] : 7^13
= 7^13(5 + 11.7) : 7^13
= 7^13.85 : 7^13
= 85

e. S = 2 + 2^2 + 2^3 + 2^4 +...+ 2^99 + 2^100
2S = 2^2 + 2^3 + 2^4 + 2^5 +...+ 2^100 + 2^101
2S - S = (2^2 + 2^3 + 2^4 + 2^5 +...+ 2^100 + 2^101) - (2 + 2^2 + 2^3 + 2^4 +...+ 2^100)
S = 2^101 - 2
f. S = 3 + 3^2 + 3^3 +...+ 3^15
3S = 3^2 + 3^3 + 3^4 +...+ 3^16
3S - S = (3^2 + 3^3 + 3^4 +...+ 3^16) - (3 + 3^2 + 3^3 +...+ 3^15)
2S = 3^16 - 3
S = (3^16 - 3)/2
(Phần g làm tương tự như 2 phần này nha bạn)