A = 1+32+34+36+.....+3100
32A = 32+34+36+38+....+3102
8A = 32A-A = 3102-1
=> A = \(\frac{3^{102}-1}{8}\)
A = 1 + 32 + 34 + 36 + ... + 398 + 3100
3A= 32 + 34 + 36 + ... + 398 + 3100 + 3101
3A-A= (32 + 34 + 36 + ... + 398 + 3100 + 3101) - (1 + 32 + 34 + 36 + ... + 398 + 3100)
2A= 3101 - 1
A= (3101 - 1) :2
Vậy ____________________