A=3+32+33+34+…+3100
=> 3A=32+33+34+35+…+3101
=>3A-A=32+33+34+35+…+3101-3-32-33-34-…-3100
=> 2A=3101-3
=> A=(3101-3):2
Vậy A=(3101-3):2
3C=32+33+34+35+............+3101
3C-C=(32+33+34+.........+3101)-(3+32+33+.........+3100)
2C=3101-3
=>C=\(\frac{3^{101}-3}{2}\)