1/2+1/12+1/30+...+1/9120+1/9506+1/9900. / 50-50/51-51/52-...-97/98-98/99-99/100
Cho S = 1/51 + 1/52 + 1/53 + ... + 1/100 . CMR 7/12 < S < 5/6
CM: 1/51 +1/52+1/53 +................+1/100 < 5/6
Chứng Minh:
1/1*2+1/3*4+1/5*6+...+1/97*98+1/99*100=1/51+1/52+1/53+...+1/99+1/100
A=1/2+1/6+...+1/9900
B=1/50+1/51+...+1/100
Tính A-B
A = \(\frac{1}{51}+\frac{1}{52}+\frac{1}{53}+...+\frac{1}{100}\) . Chứng minh : \(\frac{7}{12}< A< \frac{5}{6}\)
M=1/2-3/4+5/6-7/8+...+197/198-199/200
N=1/51+1/52+1/53+...+1/100
Tính M : N
Cho M= 1/2-3/4+5/6-7/8+...+197/198-199/200
N= 1/51+1/52+1/53+...+1/100
Tính N:M
cho A = 1/1*2+1/3*4+...+1/99*100 và B= 2015/51+2015/52+2015/53+...+2015/100. Chứng minh rằng B chia hết cho A