S=1+3+5+...+99+101
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)
2S = \(\frac{2}{1.3}+\frac{2}{3.5}+....+\frac{2}{99.101}=\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-....-\frac{1}{101}\)
\(2S=1-\frac{1}{101}\)
2S + 1/101 = \(1-\frac{1}{101}+\frac{1}{101}=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, S= 1/1*2 + 1/2*3 + 1/3*4 +...+1/99*100
S= 1/1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 +...+ 1/99 - 1/100
S= 1/1 - 1/100
S= 100/100 - 1/100
S= 99/100
b, S= 1/1*3 + 1/3*5 + 1/5*7 +...+1/99*101
S= 1/2* (2/1*3 + 2/3*5 + 2/5*7 +...+ 2/99*101)
S= 1/2* (1/1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 +...+ 1/99 - 1/101)
S= 1/2* (1/1 - 1/101)
S= 1/2* (101/101 - 1/101)
S= 1/2* 100/101
S= 50/101
Chúc bạn học tốt nha
![](https://rs.olm.vn/images/avt/0.png?1311)
\(6S=1.3.6+3.5.6+5.7.6+...+99.101.6\)
\(6S=1.3.\left(5+1\right)+3.5.\left(7-1\right)+5.7.\left(9-3\right)+...+99.101.\left(103-97\right)\)
\(6S=1.3.1+1.3.5-1.3.5+3.5.7-3.5.7+5.7.9-...-97.99.101+99.101.103\)
\(6S=1.3+99.101.103\Rightarrow\left(3+99.101.103\right):6\)
![](https://rs.olm.vn/images/avt/0.png?1311)
bạn ấn vào đúng 0 sẽ ra kết quả, mình làm bài này rồi dễ lắm
![](https://rs.olm.vn/images/avt/0.png?1311)
\(S=\frac{2}{-1.3}+\frac{2}{-3.5}+...+\frac{2}{-99.101}\)
\(S=\frac{3-\left(-1\right)}{-1.3}+\frac{5-\left(-3\right)}{-3.5}+...+\frac{101-\left(-99\right)}{-99.101}\)
\(S=\frac{3}{-1.3}-\frac{-1}{-1.3}+\frac{5}{-3.5}-\frac{-3}{-3.5}+...+\frac{101}{-99.101}-\frac{-99}{-99.101}\)
\(S=\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{99}-\frac{1}{101}\)
\(S=\frac{1}{1}-\frac{1}{101}\)
\(S=\frac{100}{101}\)
\(S=-\left(\frac{2}{1.3}+\frac{2}{3.5}+...+\frac{2}{99.101}\right)=-\left(\frac{3-1}{3.1}+\frac{5-3}{3.5}+...+\frac{101-99}{99.101}\right)\)
\(=-\left(\frac{3}{3.1}-\frac{1}{3.1}+\frac{5}{3.5}-\frac{3}{3.5}+...+\frac{101}{99.101}-\frac{99}{99.101}\right)\)
\(=-\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{99}-\frac{1}{101}\right)\)
=\(-\left(1-\frac{1}{101}\right)=-\frac{100}{101}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
S=1 + 3 + 5 + ... + 99 + 101
=> S = ( 101 + 1 ) . 51 : 2
=> S = 102 . 51 ; 2
=> S = 5202 : 2
=> S = 2601
Ta có: 1+3+5+...+99+101
Tổng trên là:(1+101).2= 204
Đ/S: 204
k cho mk nha!!!!