s1=1/5+1/13+1/25+1/41+1/61+1/85+1/113<1/2
s2=1/3-2/3^2+3/3^3-4/3^4+...+99/3^99-100/3^100<3/16
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CMR:
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\(S1=\frac{1}{5}+\frac{1}{13}+\frac{1}{25}+\frac{1}{41}+\frac{1}{61}+\frac{1}{85}+\frac{1}{113}<\frac{1}{2}\)
CMR: 1/5+1/13+1/25+1/41+1/61+1/85+1/113<1/2
so sánh A=1/5+1/13+1/25+1/41+1/61+1/85+1/113 với 1/2
1- ( 1/5 +1/13+1/25+1/41+1/61+1/85+1/113)
So sánh với 1/2.
8 tháng 4 2023 lúc 18:23
Chứng minh rằng: 1/3+1/13+1/25+1/41+1/61+1/85+1/113<2
chung minh rang:
1/5+1/13+1/25+1/41+1/61+1/85+1/113<1/2
1/5+1/13+1/25+1/41+1/61+1/85+1/113
=1/5+(1/13+1/25+1/41)+(1/85+1/61+1/113)<15+1/12+1/12+1/12+1/60+1/60+1/60
..............................................................<1/5+1/4+1/20
..............................................................<4/20+5/20+1/20
..............................................................<1/2
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Xem thêm câu trả lời
ai giúp mk bài này với, nhanh lên nha
1/5+1/13+1/25+1/41+1/61+1/85+1/113<1/2
Chứng tỏ rằng
1/5/1/13+1/25+1/41+1/61+1/85+1/113<1/2
Gíup mik nha gấp lắm
xem lại đề,1/5/1/13 là sao bạn,có phải là 1/5+1/13 không
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Chứng minh rằng
1/5+1/13+1/25+1/41+1/61+1/85+1/113 < 2
Bài này mk ko hiểu.Giải hộ mk vs >.<
đặt A=\(\dfrac{1}{5}+\dfrac{1}{13}+\dfrac{1}{25}+\dfrac{1}{41}+\dfrac{1}{61}+\dfrac{1}{85}+\dfrac{1}{113}\)
= \(\dfrac{1}{5}+(\dfrac{1}{13}+\dfrac{1}{25}+\dfrac{1}{41})+(\dfrac{1}{61}+\dfrac{1}{85}+\dfrac{1}{113})\)
=> A< \(\dfrac{1}{5}+(\dfrac{1}{12}+\dfrac{1}{12}+\dfrac{1}{12})+(\dfrac{1}{60}+\dfrac{1}{60}+\dfrac{1}{60})\)
A<\(\dfrac{1}{5}+\dfrac{1}{4}+\dfrac{1}{20}\)=\(\dfrac{1}{2}\)
vậy A<\(\dfrac{1}{2}\),<2=> A<2 (đpcm)
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