s= 1/5+1/13+1/14+1/15+1/61+1/62+1/63.CMR:3/7<S<1/2
CMR : 1/3+1/5+1/13+1/14+1/15+1/61+1/62+1/63<5/6
CMR : 1/3+1/5+1/13+1/14+1/15+1/61+1/62+1/63 < 5/6
CHO 1/5+1/13+1/14+1/15+1/61+1/62+1/63
cHỨNG minh 3/7<S<1/2
CMR : S = 1/5+1/13+1/14+1/15+1/61+1/62+1/63 < 1/2
minh thach ai lam duoc bai nay
\(S=\frac{1}{5}+\left(\frac{1}{13}+\frac{1}{14}+\frac{1}{15}\right)+\left(\frac{1}{61}+\frac{1}{62}+\frac{1}{63}\right)\)
\(\Rightarrow S< \frac{1}{5}+\frac{1}{12}.3+\frac{1}{60}.3\)
\(\Rightarrow S< \frac{1}{5}+\frac{1}{4}+\frac{1}{20}\)
\(\Rightarrow S< \frac{1}{2}\)
CMR: 1/5 + 1/13 +1/14 +1/15 +1/61 +1/62 + 1/63 < 1/2
chứng minh rằng s=1/5+1/13+1/14+1/15+1/61+1/62+1/63<1/2
Chứng minh S = 1/5 +1/13+ /14+1/15+1/61+1/62+1/63 < 1/2
Ta có:
\(\frac{1}{5}=\frac{1}{5}\)
\(\frac{1}{13}+\frac{1}{14}+\frac{1}{15}
Ta có: \(S=\frac{1}{5}+\left(\frac{1}{13}+\frac{1}{14}+\frac{1}{15}\right)+\left(\frac{1}{61}+\frac{1}{62}+\frac{1}{63}\right)
CMR : S = 1/5+1/13+1/14+1/15+1/61+1/62+1/63 < 1/2
Mình thách ai làm được bài này ai làm nhanh nhất mình tick nha
S=1/5=(1/13+1/14+1/15)+(1/61+1/62+1/63)
suy ra S<1/5+1/12x3+1/60x3
S<1/5+1/4+1/20
=>S<1/2
chứng minh rằng: S=1/5+1/13+1`/14+1/15+1/61+1/62+1/63<1/2
\(\frac{1}{5}+\frac{1}{13}+\frac{1}{14}+\frac{1}{15}+\frac{1}{61}+\frac{1}{62}+\frac{1}{63}
Ta có:
S=1/5+(1/13+1/14+1/15)+(1/61+1/62+1/63)<1/5+1/12.3+1/60.3
=>S<1/5+1/4+1/20=10/20
Hay S<1/2