A = 3 + 2 + 22 + 23 + ... + 250
2A = 6 + 22 + 23 + 24 + ... + 251
2A - A = ( 6 + 22 + 23 + 24 + ... + 251 ) - ( 3 + 2 + 22 + 23 + ... + 250 )
A = ( 6 + 251 ) - ( 3 + 2 )
A = ( 6 - 3 ) + ( 251 - 2 )
A = 3 + 251 - 2
A = 251 + ( 3 - 2 )
A = 251 + 1
A = 3 + 2 + 22 + 23 + ..... + 2 50
A-3 = 2 + 22 + 23 + ..... + 2 50
(A-3) .2 = 22 + 23 + 24 + ..... + 2 51
(A-3) .2 - (A-3) = 22 + 23 + 24 + ..... + 2 51 - 2 - 22 - 23 - ..... - 2 50
A-3 = 251 - 2
A = 251 - 2 + 3
A = 251 +1
Vì số 251 to lắm nên giữ nguyên nhé !
A = 3 + 2 + 2 2 + 2 3 + ... + 2 50
2A = 6 + 2 2 + 2 3 + 2 4 + ... + 2 51
2A - A = ( 6 + 2 2 + 2 3 + 2 4 + ... + 2 51 )
- ( 3 + 2 + 2 2 + 2 3 + ... + 2 50 )
A = 6 + 5 51 - 3 - 2
A = 5 51 + 1
