1/97 chứ sao lại 1/91!
giải:
đặt :1/5+1/14+1/28+1/44+1/61+1/85+1/97 =A
ta có :A=1/5(1/14+1/28+1/44)+(1/61+1/85+1/97)
A<1/5(1/14.3)+(1/61.3)
A<1/5+3/14+3/61
A<1/5+3/12+1/20
A<1/5+1/4+1/20
=>A<1/2
VẬY dpcm
chứng minh rằng 1/5+1/14+1/28+1/44+1/61+1/85+1/91<1/2
Chứng minh rằng:
\(\frac{1}{5}+\frac{1}{14}+\frac{1}{28}+\frac{1}{44}+\frac{1}{61}+\frac{1}{85}+\frac{1}{91}<\frac{1}{2}\)
B=1/5+1/14+1/28+1/44+1/61+1/85 Chứng minh rằng B<1/2
ứng tỏ rằng 1/5 +1/14 + 1/28 + 1/44 +1/61 + 1 / 85 + 1 / 91 < 1/2
1. Chứng minh rằng : 1/5 +1/14 +1/28 +1/44 +1/61+ 1/85 +1/91 < 1/2
2. Chứng tỏ rằng : 1/5+1/6+1/7+...+1/16+1/17 < 2
3. Tính: A= [878787/9595953+ (-8787/9595)] * 1234621/5678765
4. So sánh : 10^8+2/10^8-1 ; B= 10^8/10^8-3
chứng minh: 1/5 + 1/14+1/28 +1/44 + 1/61+1/85+1/97 <1/2
chứng minh
1/5+1/14+1/28+1/44+1/61+1/85+1/97<1/2
chứng tỏ rằng
A= 1/5 + 1/14 + 1/28 + 1/44 + 1/61 + 1/85 + 1/97 < 1/2
Chứng minh rằng: \(\frac{1}{5}+\frac{1}{14}+\frac{1}{28}+\frac{1}{44}+\frac{1}{61}+\frac{1}{85}+\frac{1}{97}<\frac{1}{2}\)
