B=1/1.3+1/3.5+...+1/2015.2017
B= 1/2 . 2. ( 1/1.3+1/3.5 + .... + 1/2015 .2017)
B = 1/2 . ( 2/1.3 + 2/3.5 + ......+ 2/2015.2017)
B = 1/2. ( 1/1+ -1/3 + 1/3 + -1/5 + 1/5 +....+ 1/2015 + -1/2017)
B= 1/2 . ( 1/1 + -1 / 2017) = 1/2 . 2016 / 2017 = 2016 / 4034
Vậy B = 2016 / 4034 nha bn.pham hong thai
1/1.3+1/3.5+1/5.7+....+1/2015.2017
1/1.3+1/3.5+.....+1/2015.2017
\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2015.2017}\)
-2/1.3-2/3.5-2/5.7-2/7.9-.....-2/2015.2017-1/27
B = (1+1/1.3)(1+1/2.4)(1+1/3.5)......(1+1/2014.2016)(1+ 1/2015.2017)
Nếu có thể thì các bạn giải ra giùm mik nha
\(ChoA=\left(1+\frac{1}{1.3}\right).\left(1+\frac{1}{3.5}\right).\left(1+\frac{1}{5.7}\right).....\left(1+\frac{1}{2015.2017}\right)\)
1.3+3.5+5.7+..........+2015.2017
Tính tổng các ps sau
a,\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2017.2018}\)
b,\(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2015.2017}\)
3/1.3+3/3.5+...+3/2015.2017
