- Giải phương trình, bất phương trình Hoán vị - Ch...

A \(A_n^n = (n - 1)!\)

B \(A_n^n = (n + 1)!\)

C \(A{_n^n} = \frac{{n!}}{{(n - 1)}}\)  

D \(A_n^n = n!\)

A \(x = 10\)

B \(x = 11\)         

C \(x = 11\)hay \(x = 10\).

D \(x = 20\)

A \(C_n^k = \frac{{n!}}{{\left( {n - k} \right)!}}\)

B \(A_n^k = k!.C_n^k\)

C \(C_n^{n - k} = C_n^k\)

D \(C_n^k + C_n^{k + 1} = C_{n + 1}^{k + 1}\)

A \(C_{14}^3 = C_{14}^{11}\)

B \(C_{10}^3 + C_{10}^4 = C_{11}^4\)

C \(C_4^0 + C_4^1 + C_4^2 + C_4^3 + C_4^4 = 16\)

D \(C_{10}^4 + C_{11}^4 = C_{11}^5\)

A \(n = 6\)

B \(n = 5\)

C \(n = 8\)

D không tồn tại

A \(0.\)

B \(1.\)

C \(2.\)     

D \(6.\)

A \(x = 10\)         

B \(x{\rm{ }} = {\rm{ }}9\)

C \(x = 11\)

D \(x{\rm{ }} = {\rm{ }}9\,\) và \(x{\rm{ }} = {\rm{ }}\frac{{91}}{9}\).

A \(n = 2\) hoặc \(n = 4\)

B \(n = 5\)

C \(n = 4\)

D \(n = 3\)

A \(n = 3\)

B \(n = 6\)

C \(n = 4\)

D \(n = 8\)

A \(11\)

B \(12\)

C \(10\)

D \(9\)

A \(25\)

B \(24\)

C \(26\)

D \(23\)

A \(3;\;4;\;\,5\)

B \(5;\;\,6;\;7\)

C \(6;\;8;\;2\)

D \(7;\;8;\;\,9\)

A \(x = 1;y = 5\)

B \(x = 2;y = 1\)

C \(x = 2;y = 5\)

D \(x = 1;y = 3\)

A \(n = 3\)

B \(n = 5\)

C \(n = 3\) hoặc \(n = 4\).

D \(n = 4\)

A \(\frac{{61}}{{90}}\)

B \(\frac{{59}}{{90}}\)            

C \(\frac{{29}}{{45}}\)

D \(\frac{{57}}{{90}}\)

A 3

B 4

C 5

D 6

A \(\frac{9}{{10}}\)

B \(\frac{{10}}{9}\)

C \(\frac{1}{9}\)

D \(\frac{3}{4}\)

A \(x = 6;y = 3\)

B \(x = 2;y = 1\).

C \(x = 2;y = 5\)

D \(x = 1;y = 3\)

A \(P = 2017 - \frac{1}{{2018!}}\)

B \(P = 2017 - \frac{1}{{2017!}}\)

C \(P = 2018 - \frac{1}{{2017!}}\)

D \(P = 2018 - \frac{1}{{2018!}}\)

A \(\frac{8}{{9}}\)

B \frac{{10}}{9}\)

C \(\frac{1}{9}\)

D \(9\)