\(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+......+\frac{1}{380}\)
=\(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...............+\frac{1}{19.20}\)
=\(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+..............+\frac{1}{19}-\frac{1}{20}\)
=\(\frac{1}{2}-\frac{1}{20}\)
=\(\frac{9}{20}\)
1/6+1/12+1/20+.....+1/380............0,4
1/6+1/12+1/20+...+1/380....0.4
Hãy so sánh :
1/ 6 + 1/ 12 + 1/ 20 + ... + 1/ 380 ........................ 0 , 4
1 phần 2 cộng 1 phần 6 cộng 1 phần 12 cộng 1 phần 20 cộng .... cộng 1 phần 380
1/5+1/12+1/20+...+1/380........0.4
a.A=1 1/2 x 1 1/3 x 1 1/4 x 1 1/5 x...x1 1/2020 x 1 1/2021
b.B=1 1/2 + 1 1/6 + 1 1/12 +1 1/20+ ... + 1 1/380 + 1 1/420
c.C=1 6/8 x 1 6/18 x 1 6/30 x 1 6/44 x ... x 1 6/10700
1\(\frac{1}{12}-\frac{1}{20}-...-\frac{1}{380}=?\)
a.A=1 1/2 x 1 1/3 x 1 1/4 x 1 1/5 x...x1 1/2020 x 1 1/2021
b.B=1 1/2 + 1 1/6 + 1 1/12 +1 1/20+ ... + 1 1/380 + 1 1/420
c.C=1 6/8 x 1 6/18 x 1 6/30 x 1 6/44 x ... x 1 6/10700
a.A=1 1/2 x 1 1/3 x 1 1/4 x 1 1/5 x...x1 1/2020 x 1 1/2021
b.B=1 1/2 + 1 1/6 + 1 1/12 +1 1/20+ ... + 1 1/380 + 1 1/420
c.C=1 6/8 x 1 6/18 x 1 6/30 x 1 6/44 x ... x 1 6/10700
