![](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)
\(\left(\frac{5}{12}+\frac{1}{2}.\frac{1}{3}\right):\left(2.\frac{1}{3}-1.\frac{5}{12}\right)\)
\(=\left(\frac{5}{12}+\frac{1}{6}\right):\left(\frac{2}{3}-\frac{5}{12}\right)\)
\(=\frac{7}{12}:\frac{1}{4}\)
\(=\frac{7}{3}\)
_Chúc bạn học tốt_
![](https://rs.olm.vn/images/avt/0.png?1311)
sửa đề nhé:
\(\frac{5}{1\times3}+\frac{5}{3\times5}+...+\frac{5}{99\times101}\)
\(5\times\frac{1}{2}\times\left(\frac{2}{1\times3}+\frac{2}{3\times5}+...+\frac{2}{99\times101}\right)\)
\(=\frac{5}{2}\times\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{101}\right)\)
\(=\frac{5}{2}\times\left(1-\frac{1}{101}\right)\)
\(=\frac{5}{2}\times\frac{100}{101}\)
\(=\frac{250}{101}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(B=\dfrac{1}{4}\times\left(\dfrac{4}{1\times5}+\dfrac{4}{5\times9}+\dfrac{4}{9\times13}+...+\dfrac{4}{125\times129}\right)\)
\(=\dfrac{1}{4}\times\left(1-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{9}+...+\dfrac{1}{125}-\dfrac{1}{129}\right)\)
\(=\dfrac{1}{4}\times\left(1-\dfrac{1}{129}\right)=\dfrac{1}{4}\times\dfrac{128}{129}=\dfrac{32}{129}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(D=\dfrac{1}{1\cdot5}+\dfrac{1}{5\cdot9}+...+\dfrac{1}{21\cdot25}\)
\(4D=\dfrac{4}{1\cdot5}+\dfrac{4}{5\cdot9}+...+\dfrac{4}{21\cdot25}\)
\(4D=1-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{9}+...+\dfrac{1}{21}-\dfrac{1}{25}\)
\(4D=1-\dfrac{1}{25}=\dfrac{24}{25}\)
\(D=\dfrac{24}{25}\cdot\dfrac{1}{4}=\dfrac{4\cdot6}{25\cdot4}=\dfrac{6}{25}\)
1/1x5/5=1 nha bạn
1/1*5/5=5/5=1