Cho A=1-1/2+1/3-1/4+1/5-1/6+...+1/49-1/50.Chung minh A<5/6
cho A= 1-1/2+1/3-1/4+1/5-1/6+1/7-1/8+....1/49-1/50. Chứng minh A<5/6
cho a=1=1\2+1\3-1\4+1\5...+1\49-1\50.Chung to rang 7\12<4<5\6
cho A=1-1/2+1/3-1/4+1/5-1/6+...+1/49-1/50
chứng minh rằng 7/12<A<5/6
cho A=1 - 1/2 + 1/3 - 1/4 +1/5 - 1/6 +..............+1/49 -1/50
Chứng tỏ 7/12<A<5/6
1/1*2+1/3*4+1/5*6+...+1/49*50=1/26+1/27+1/28+...+1/50
1/1*2+1/3*4+1/5*6+...+1/99*100
1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 +...+ 1/49 - 1/50 = ?
chứng minh
1/1*2+1/3*4+1/5*6+...+1/49*50=1/26+1/27+....+1/50
chung minh rang:1/(1*2)+1/(3*4)+1/(5*6)+.....+1/(49*50)=1/26+1/27+1/28+....+1/50
