tính B= 1/16 + 6/16.26 + 6/26.36 + 6/36.46 + .....+ 6/2006.2016
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L
16 tháng 11 2019
ai nhanh giup minh di roi minh cho nick "lien quan mobile" rank vang
16 tháng 11 2019
B=1/16+ 6/16.26+ 6/26.36+ ..................+ 6/2006.2016
B=1/16+ 6. (1/16.26+ 1/26.36 +.................+ 1/2006.2016)
10B=1/16+6.(1/16- 1/2016)
10B=7.1/16 - 1/336
10B=7/16 - 1/336
10B=73/168
B=73/1680
làm hơi tắt bạn cố hiểu nhé
17 tháng 3 2016
\(B=\frac{1}{16}+\frac{6}{16.26}+\frac{6}{26.36}+\frac{6}{36.46}+...+\frac{6}{2006.2016}\) =\(B=\frac{1}{16}+\frac{3}{5}\left(\frac{10}{16.26}+\frac{10}{26.36}+\frac{10}{36.46}+...+\frac{10}{2006.2016}\right)\)
\(B=\frac{1}{16}+\frac{3}{5}\left(\frac{1}{16}-\frac{1}{26}+\frac{1}{26}-\frac{1}{36}+\frac{1}{36}-\frac{1}{46}+...+\frac{1}{2006}-\frac{1}{2016}\right)\)
\(B=\frac{1}{16}+\frac{3}{5}\left(\frac{1}{16}-\frac{1}{2016}\right)\)
đến đây thì ổn rồi
16 tháng 12 2022
\(=\dfrac{1}{16}+\dfrac{1}{16}-\dfrac{1}{26}+...+\dfrac{1}{2006}-\dfrac{1}{2016}\)
=1/8-1/2016
=251/2016
Y
2
Q
31 tháng 12 2017
\(B=\frac{1}{16}+\frac{6}{16.26}+\frac{6}{26.36}+...+\frac{6}{2006.2016}\)
\(B=\frac{1}{16}+6\left(\frac{1}{16.26}+\frac{6}{26.36}+...+\frac{6}{2006.2016}\right)\)
\(B=\frac{1}{16}+\frac{6}{10}\left(\frac{1}{16}-\frac{1}{26}+\frac{1}{26}-\frac{1}{36}+...+\frac{1}{2006}-\frac{1}{2016}\right)\)
\(B=\frac{1}{16}+\frac{6}{10}\left(\frac{1}{16}-\frac{1}{2016}\right)\)
\(B=\frac{1}{16}+\frac{6}{10}.\frac{125}{2016}\)
\(B=\frac{1}{16}+\frac{25}{672}\)
\(B=\frac{67}{672}\)
1 tháng 4 2016
x-y-z=0=>x=y+z
=>z=x-y;=>y=x-z
\(=>B=\left(1-\frac{z}{x}\right)\left(1-\frac{x}{y}\right)\left(1-\frac{y}{z}\right)=\left(1-\frac{x-y}{x}\right)\cdot\left(1-\frac{y+z}{y}\right)\cdot\left(1+\frac{x-z}{z}\right)\)
1 tháng 4 2016
Câu a cậu ghi sai đầu bài rồi hay sao í! phải là \(\frac{6}{36.46}\) chứ
29 tháng 5 2017
a, \(A=\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+...+\dfrac{1}{299.300}\)
\(=\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{299}-\dfrac{1}{300}\)
\(=1-\dfrac{1}{300}=\dfrac{299}{300}\)
Vậy \(A=\dfrac{299}{300}\)
b, \(B=\dfrac{10^2}{16.26}+\dfrac{10^2}{26.36}+...+\dfrac{10^2}{86.96}\)
\(=10\left(\dfrac{10}{16.26}+\dfrac{10}{26.36}+...+\dfrac{10}{86.96}\right)\)
\(=10\left(\dfrac{1}{16}-\dfrac{1}{26}+\dfrac{1}{26}-\dfrac{1}{36}+...+\dfrac{1}{86}-\dfrac{1}{96}\right)\)
\(=10\left(\dfrac{1}{16}-\dfrac{1}{96}\right)\)
\(=10.\dfrac{5}{96}=\dfrac{25}{48}\)
Vậy...
DH
29 tháng 5 2017
a,\(A=\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+.......+\dfrac{1}{299.300}\)
\(A=\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{299}-\dfrac{1}{300}\)
(do \(\dfrac{n}{a.\left(a+n\right)}=\dfrac{1}{a}-\dfrac{1}{a+n}\) với mọi \(a\in N\)*)
\(A=\dfrac{1}{1}-\dfrac{1}{300}=\dfrac{299}{300}\)
3 tháng 5 2016
\(\frac{15.\left(\frac{1}{616}.\frac{1}{6.16}.\frac{1}{6.16}\right)}{33.\left(\frac{1}{6.16}.\frac{1}{6.16}.\frac{1}{6.16}\right)}=\frac{15}{35}\)
\(B=\frac{1}{16}+\frac{6}{16.26}+\frac{6}{26.36}+....+\frac{6}{2006.2016}\)
\(=\frac{6}{6.16}+\frac{6}{16.26}+\frac{6}{26.36}+....+\frac{6}{2006.2016}\)
\(=\frac{6}{10}\left(\frac{1}{6}-\frac{1}{16}+\frac{1}{16}-\frac{1}{26}+...+\frac{1}{2006}-\frac{1}{2016}\right)\)
\(=\frac{3}{5}\left(\frac{1}{6}-\frac{1}{2016}\right)\)
\(=\frac{67}{672}\)
\(B=\frac{1}{16}+\frac{6}{16\cdot26}+\frac{6}{26\cdot36}+...+\frac{6}{2006\cdot2016}\)
\(B=\frac{1}{16}+6\left(\frac{1}{16\cdot26}+\frac{1}{26\cdot36}+...+\frac{1}{2006\cdot2016}\right)\)
\(B=\frac{1}{16}+6\left[\frac{1}{10}\left(\frac{10}{16\cdot26}+\frac{10}{26\cdot36}+...+\frac{10}{2006\cdot1016}\right)\right]\)
\(B=\frac{1}{16}+6\left[\frac{1}{10}\left(\frac{1}{16}-\frac{1}{26}+\frac{1}{26}-\frac{1}{36}+...+\frac{1}{2006}-\frac{1}{2016}\right)\right]\)
\(B=\frac{1}{16}+6\left[\frac{1}{10}\left(\frac{1}{16}-\frac{1}{2016}\right)\right]\)
\(B=\frac{1}{16}+6\cdot\left[\frac{1}{10}\cdot\frac{125}{2016}\right]\)
\(B=\frac{1}{16}+6\cdot\frac{26}{4032}\)
\(B=\frac{1}{16}+\frac{25}{672}\)
\(B=\frac{57}{672}\)