A = 1 + 3 + 32 + 33 +....+ 3100
3A = 3 + 32 + 33 + 34 +...+3101
=> 2A = 3A - A = 3101 - 1
=> A = \(\frac{3^{101}-1}{2}\)
Ta có: A=1+3+32+33+.........+3100 (1)
=> 3A= 3+32+33+34+...........+3101 (2)
Lấy (2)-(1) ta có:
3A-A=(3+32+33+34+............+3101)-(1+3+32+33+.............+3100)
=> 2A=3101-1
\(\Rightarrow A=\frac{3^{101}-1}{2}\)
A = 1 + 3 + 32 + 33 + ....+ 3100
=> 3A= 3 + 32 + 33 + ....+ 3100
3A -A=( 3 +32 + 33 +..... + 3101
2A =\(\frac{3^{101}-1}{2}\)
Ta có: A = 1 + 3 + 32 + 33 +....+ 3100
=> 3A = 3 + 32 + 33 + 34 +...+3101
=> 3A - A = 3101 - 1
=> 2A = 3101 - 1
=> A = 3101 - 1/2
