![](https://rs.olm.vn/images/avt/0.png?1311)
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\dfrac{-11}{7}+\dfrac{1}{16}+\dfrac{6}{7}=\dfrac{-5}{7}+\dfrac{1}{16}=\dfrac{-80+7}{112}=\dfrac{-73}{112}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
B= 3/2.4/3. ....2001/2000
B = 3.4....2001/2.3....2000
B =2001/2
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{1}{n\left(n+1\right)}=\frac{1}{n}-\frac{1}{n+1}\)
=> \(\frac{1}{x+2000}-\frac{1}{x+2001}+\frac{1}{x+2001}-\frac{1}{x+2002}+....+\frac{1}{x+2006}-\frac{1}{x+2007}=\frac{7}{8}\)
<=> \(\frac{1}{x+2000}-\frac{1}{x+2007}=\frac{7}{8}\)
<=> \(\frac{7}{\left(x+2000\right)\left(x+2007\right)}=\frac{7}{8}\Leftrightarrow\left(x+2000\right)\left(x+2007\right)=8\)
=> x = -1999 hoặc x = - 2008
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-\frac{3}{5}.\frac{2}{7}+-\frac{3}{5}.\frac{5}{7}+2\frac{3}{5}\)
\(=-\frac{3}{5}\left(\frac{2}{7}+\frac{5}{7}\right)+2\frac{3}{5}\)
\(=-\frac{3}{5}+\frac{13}{5}\)
\(=\frac{10}{5}=2\)
Đặt a=123456 ta được:
\(\frac{2000}{123456^2-123457.123455}=\frac{2000}{a^2-\left(a+1\right)\left(a-1\right)}=\frac{2000}{a^2-a.\left(a-1\right)-1.\left(a-1\right)}\)
\(=\frac{2000}{a^2-a^2+a-a+1a^2a^{ }}=\frac{2000}{1}=2000\)