bài a mình nghĩ rút gọn rồi tính bạn thử làm coi
Bài a:
1.3.5......199 = 1.2.3.4......199.200/2.4.6.....200
= 1.2.3.4.........199.200/1.2.3.4....100.2100
=101.102.....200/2.2......2.2
=101/2 . 102/2 . 103/2 . ..... . 200/2
bài a mình nghĩ rút gọn rồi tính bạn thử làm coi
Bài a:
1.3.5......199 = 1.2.3.4......199.200/2.4.6.....200
= 1.2.3.4.........199.200/1.2.3.4....100.2100
=101.102.....200/2.2......2.2
=101/2 . 102/2 . 103/2 . ..... . 200/2
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
Chứng minh rằng: 1/3+1/13+1/25+1/41+1/61+1/85+1/113<2
Chứng minh:
c.\(\frac{11}{15}< \frac{1}{21}+\frac{1}{22}+\frac{1}{23}+...+\frac{1}{59}+\frac{1}{60}< \frac{3}{2}\)
b.\(\frac{1}{5}+\frac{1}{13}+\frac{1}{25}+\frac{1}{41}+\frac{1}{61}+\frac{1}{85}+\frac{1}{113}< \frac{1}{2}\)
a.\(\frac{1}{4}+\frac{1}{16}+\frac{1}{36}+\frac{1}{64}+\frac{1}{100}+\frac{1}{144}+\frac{1}{196}< \frac{1}{2}\)
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
chứng tỏ: a, 1/5 + 1/6 + 1/7 + .... + 1/17 < 2
b, 1/5 + 1/13 + 1/25 + 1/41 + 1/61 + 1/85 + 1/113 < 1/2
1- ( 1/5 +1/13+1/25+1/41+1/61+1/85+1/113)
So sánh với 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
Chứng minh
a)B=1/10+1/11+...+1/28 > 1
b)C=1/10.1/11+1/11.1/12+...+1/20.1/21 > 1/20
c)E=1/51+1/52+...+1/100 > 1
d)F=1/2^2+1/3^2+...+1/9^2
Chứng minh 2/5<F<8/9
e)H=1/31+1/32+...+1/60
Chứng minh 3/5<H<4/5
f)K=1/21+1/22+...+1/30>1/3