- Dạng toán tính tổng và các câu hỏi khác (có lời...

A \({2^{2017}} - 1\)

B \({2^{2016}}\)

C \({2^{2017}}\)

D \({2^{2016}} - 1\)

A \({7^n}\)       

B \({5^n}\)       

C \({6^n}\)

D \({4^n}\)

A \(0\) nếu \(n\) chẵn.

B \(0\) nếu \(n\) lẻ.               

C \(0\) nếu \(n\) hữu hạn.     

D \(0\) trong mọi trường hợp.

A \(n = 10\)

B \(n = 5\)

C \(n = 9\)

D \(n = 11\)

A \({2^{n - 2}}\)

B \({2^{n - 1}}\)

C \({2^{2n - 2}}\)

D \({2^{2n - 1}}\)

A \(77520\)

B \(1860480\)

C \(1048576\)

D \(81920\)

A \(A_n^2\)

B \(C_n^2\)

C \({2^n}\)

D \({3^n}\)

A \(\frac{{{2^{n + 1}} + 1}}{{n + 1}}\)

B \(\frac{{{2^{n + 1}} + 1}}{{n + 1}}\)

C \(\frac{{{2^{n + 1}} - 1}}{{n + 1}} + 1\)

D \(\frac{{{2^{n + 1}} - 1}}{{n + 1}} - 1\)

A \(2n{.2^{n - 1}}\)

B \(n{.2^{n + 1}}\)

C \(2n{.2^{n + 1}}\)

D \(n{.2^{n - 1}}\)

A \(n(n - 1){2^{n - 2}}\)          

B \(n(n + 2){2^{n - 2}}\)

C \(n(n - 1){2^{n - 3}}\)

D \(n(n - 1){2^{n + 2}}\)

A \(C_{2n}^n\)

B \(C_{2n}^{n - 1}\)

C \(2C_{2n}^n\)

D \(C_{2n - 1}^{n - 1}\)

A \(P = C_{4036}^{2018}\)

B \(P = C_{4035}^{2017}\)

C \(P = C_{4034}^{2017}\)

D \(P = C_{4034}^{2018}\)

A \(S = \frac{{{3^{n + 1}} - {2^{n + 1}}}}{{n + 1}}\)

B \(S = \frac{{{3^n} - {2^{n + 1}}}}{{n + 1}}\)

C \(S = \frac{{{3^{n + 1}} - {2^n}}}{{n + 1}}\)

D \(S = \frac{{{3^{n + 1}} + {2^{n + 1}}}}{{n + 1}}\)

A \(n{.8^{n - 1}}\)

B \((n + 1){.8^{n - 1}}\)

C \((n - 1){.8^n}\)

D \(n{.8^n}\)

A \(n = 5\)

B \(n = 7\)

C \(n = 10\)

D \(n = 8\)

A \({4^{10}}\)

B \({4^9}\)

C \({2^{10}}\)

D \({2^9}\)

A \(S = \frac{{{4^{n + 1}} - {2^{n + 1}}}}{{n + 1}}\)

B \(S = \frac{{{4^{n + 1}} + {2^{n + 1}}}}{{n + 1}} - 1\)

C \(S = \frac{{{4^{n + 1}} - {2^{n + 1}}}}{{n + 1}} + 1\)

D \(S = \frac{{{4^{n + 1}} - {2^{n + 1}}}}{{n + 1}} - 1\)

A \(S = \frac{{ - n}}{{\left( {n + 1} \right)\left( {n + 2} \right)}}\)

B \(S = \frac{{2n}}{{\left( {n + 1} \right)\left( {n + 2} \right)}}\)

C \(S = \frac{n}{{\left( {n + 1} \right)\left( {n + 2} \right)}}\)      

D \(S = \frac{{ - 2n}}{{\left( {n + 1} \right)\left( {n + 2} \right)}}\)