còn ai on ko zị
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)
A xin lỗi mình viết sai đề để mình viết lại
(0,25 - 3/4) : 2/3 + (-1/2)^2
\(\left(0,25-\frac{3}{4}\right)\div\frac{2}{3}+\left(\frac{-1}{2}\right)^2\)2
\(=\left(\frac{1}{4}-\frac{3}{4}\right)\times\frac{3}{2}+\frac{1}{4}\)
\(=\frac{-1}{2}\times\frac{3}{2}+\frac{1}{4}\)
\(=\frac{-3}{4}+\frac{1}{4}\)
\(=\frac{-2}{4}=\frac{-1}{2}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Vd 3:
a) 9/10 > 5/42 b) -4/27 < 10/-73
Vd 4:
5/-6: -7/12; 5/8; 3/4
Vd 5:
x<y
Vd 6:
-16/27= -16/27> -16/29
![](https://rs.olm.vn/images/avt/0.png?1311)
Đặt A=\(\frac{6}{-7}\)+ \(\frac{9}{4}\). \(\frac{2}{15}\)- \(\frac{2}{14}\)
A = \(\frac{6}{-7}\)+ \(\frac{3}{10}\)- \(\frac{2}{14}\)
A= \(\frac{-60}{70}\)+ \(\frac{21}{70}\)- \(\frac{10}{70}\)
A= \(\frac{-7}{10}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\text{Ta có :}P=\frac{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2015}}{2014+\frac{2013}{2}+...+\frac{1}{2014}}\)
\(\Rightarrow P=\frac{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2015}}{A}\)với \(A=2014+\frac{2013}{2}+...+\frac{1}{2014}\)
\(\Rightarrow A=1+\left(1+\frac{1}{2014}\right)+\left(1+\frac{1}{2013}\right)+\left(1+\frac{1}{2012}\right)+...+\left(1+\frac{2013}{2}\right)\)
\(\Rightarrow A=\frac{2015}{2}+\frac{2015}{3}+...+\frac{2015}{2014}+\frac{2015}{2015}\)
\(\Rightarrow A=2015.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2014}+\frac{1}{2015}\right)\)
\(\text{Khi đó : }P=\frac{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2015}}{A}=\frac{\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2015}}{2015.\left(\frac{1}{2}+\frac{1}{3}+...+\frac{1}{2014}+\frac{1}{2015}\right)}\)
\(\Rightarrow P=\frac{1}{2015}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
có đừng đăng linh tinh nha
còn mk nè bn