Cho b=1+2+2mu2+2mu3+...+2mu6,A=2mu2+2mu3+2mu4+..+2mutam chứng minh rằng A=4B
1\2+1\2mu2+1\2mu3+......+1\2mu100
tinh S=1/2+1/2mu2+1/2mu3+...+1/2mu20
A=1/2+1/2mu2+1/2mu3+.....+1/2mu10
Chứng minh: A+1/2mu10=1
tim a biet a=2+2mu2+2mu3+...+2mu60
Cho S =1+2+2mu2+2mu3+...+2mu9+2mu10+2mu11.Hay so sanh Svoi 5*2mu10
A=4+2mu2+2mu3+2mu4+...+2mu20
A=2mu1+2mu2+2mu3+.........+2mu2010