đặt vế trái là A ta có
A<1/25.16+1/45.14=214/225=1-11/225
39/40=1-1/40
ta có 1.225<11.40=>1/40<11/225=>1-1/40>1-11/225=>214/225<39/40 mà A<214/225=>A<39/40(đpcm
nhớ k cho mk nha
chứng minh rằng : 1/25+1/26+1/27+...+1/54 <39/40
CMR : A = 1/25 + 1/26 + 1/27 +......+1/54 < 39/40
P= 1+2+22+23+24+25+26+27+28. Chứng minh rằng P chia hết cho 3
Chứng minh rằng: (1/26+1/27+...+1/50)÷(1/1.2+1/3.4+...+1/49.50)=1
Chứng Minh Rằng :1/26+1/27+1/28+...+1/50=1-1/2+1/3-1/4+...+1/49-1/50
Chứng minh rằng: 1/26+1/27+1/28+...+1/50=1-1/2+1/3+1/4+...+1/49-1/50
Cho S = 1 + 2 + 22 + 23 + 24 + 25 + 26 + 27. Chứng tỏ rằng S chia hết cho 3.
Chứng minh rằng : 1/26+1/27+1/28+.......+1/50=1-1/2+1/3-1/4+.....+1/49-
1/50
Chứng minh rằng:
1/26+1/27+1/28+...+1/50=1-1/2+1/3-1/4+...+1/49-1/50
