a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40
a) 3A = 3. ( 30 + 31 + 32 +...+ 311)
3A = 31 + 32 +33 +....+ 312
3A - A = 31 +32+33 +...+312 - 30 - 31-32- ...- 311
2A = 312 -1
A = (312 -1) : 2
b) A = ( 30 + 31 + 32 33) + .... + ( 38 + 39 + 310 + 311)
A = 40 + ... + 38 . ( 30 + 31 +32 +33)
A = 40 + ... + 38 .40
A = 40 . ( 1 + ...+ 38)
Vì 40 chia hết cho 40
=> 40. ( 1 + ...+38) chia hết cho 40
Vậy A chia hết cho 40