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)
a) Để x > 3.1 và < 3.6 => x = 3.2; 3.3; 3.4; 3.5; 3.56
b) Để x > 2.1 và < 2.2 => x = 2.11; 2.12; 2.13; 2.15; 2.18
Tìm 5 giá trị x sao cho
a) 3,1 < x < 3,6
b) 2,1 < x < 2,2
a) x = 3.2; 3.3; 3.4; 3.5; 3.56
b) x = 2.11; 2.12; 2.13; 2.15; 2.18
![](https://rs.olm.vn/images/avt/0.png?1311)
0,0925 < x < 1/10
0,0925 < x < 0,1
x ∈ {0,093; 0,094; 0,095; 0,096; 0,097}
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài 1: Ta có: \(4\dfrac{3}{5}+\dfrac{7}{10}< X< \dfrac{20}{3}\)
\(\dfrac{23}{5}+\dfrac{7}{10}< X< \dfrac{20}{3}\)
\(\dfrac{138}{30}< X< \dfrac{200}{3}\)
\(\Rightarrow X\in\left\{\dfrac{160}{30};\dfrac{161}{30};\dfrac{162}{30};...;\dfrac{198}{30};\dfrac{199}{30}\right\}\)
Bài 2: \(X-2019\dfrac{2}{13}=3\dfrac{7}{26}+4\dfrac{7}{52}\)
\(\Rightarrow X-\dfrac{26249}{13}=\dfrac{85}{26}+\dfrac{215}{52}\)
\(\Rightarrow X-\dfrac{26249}{13}=\dfrac{385}{52}\)
\(\Rightarrow X=\dfrac{105381}{52}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+\dfrac{1}{5\times6}+...+\dfrac{1}{38\times39}\)
\(=\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+...\dfrac{1}{38}-\dfrac{1}{39}\)
\(=\dfrac{1}{3}-\dfrac{1}{39}\)
\(=\dfrac{13}{39}-\dfrac{1}{39}\)
\(=\dfrac{12}{39}=\dfrac{4}{13}\)
`1/(3xx4)+1/(4xx5)+1/(5xx6)+...+1/(38xx39)`
`=1/3-1/4+1/4-1/5+1/5-1/6+...+1/38-1/39`
`=1/3-1/39`
`=4/13`
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
A , 2,12 ; 2,13 ; 2,14 ; 2,15 ; 2,16
B, x = 20
Học tốt ~