chung minh rang B= 1/5+1/6+1/7+.....+1/19<11/6
Những câu hỏi liên quan
Cho B=1/4+1/5+1/6+...+1/19.Hay chung to rang B>1
Ta có:\(\frac{1}{5}>\frac{1}{6}>...>\frac{1}{19}\)
=>B=\(\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{19}>\frac{1}{4}+\frac{1}{19}+\frac{1}{19}+...+\frac{1}{19}\)(15 lần 1/19)
=>B>1/4+15/19=79/76>1
=>B>1
Đúng 0
Bình luận (0)
cho B=1/4+1/5+1/6+...+1/19. Chung to rang B>1
MINH CAN GAP
NẾU AI CÓ ĐỂ NÂNG CAO GỞI QUA EMAIL CHO MÌNH VỚI ; dpduc123@gmail.com
ta có: \(\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{10}>\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+...+\frac{1}{10}=\frac{7}{10}\)( có 7 số 1/10)
\(\frac{1}{11}+...+\frac{1}{19}>\frac{1}{19}+...+\frac{1}{19}=\frac{9}{19}\)( có 9 số 1/19)
\(\Rightarrow\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{19}>\frac{7}{10}+\frac{9}{19}=1\frac{33}{190}>1\)
\(\Rightarrow B=\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{19}>1\left(đpcm\right)\)
Đúng 0
Bình luận (0)
BAI 1: TIM X BIET so tu nhien x/7 du 6. chung minh rang x.x/7 du 1
bai 2: cho 2.(a.a+b.b)=(a+b).(a+b) chung minh rang a=b
chung minh rang 1/5^3+1/6^3+1/7^3+..........+1/2004^3<1/40
Câu hỏi: chung minh rang 2 day so nay la hop so a,1+2^7+3^11+5^13+7^17+11^19 b,21^123+23^124+25^125
Câu hỏi: chung minh rang 2 day so nay la hop so a,1+2^7+3^11+5^13+7^17+11^19
b,21^123+23^124+25^125
chung to rang B=1/2^2+1/3^2+1/4^2+1/5^2+1/6^2+1/7^2+1/8^2<1
ai lam duoc minh tick cho
Ta thấy:
\(\frac{1}{2^2}< \frac{1}{1.2}\)
\(\frac{1}{3^2}< \frac{1}{2.3}\)
........................
\(\frac{1}{8^2}< \frac{1}{7.8}\)
\(\Rightarrow B< \frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{7.8}=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{7}-\frac{1}{8}=1-\frac{1}{8}< 1\)
Vậy B < 1
Đúng 0
Bình luận (0)
Cho B=\(\frac{1}{4}+\frac{1}{5}+\frac{1}{6}+...+\frac{1}{19}\)Hay chung to rang B>1
Cho B=1/5+1/6+1/7+...+1/17 .Chung to rang B<2