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Bài làm
Bạn hamlon bên dưới không làm được vậy để mình làm cho bạn .
\(\frac{3}{5}.\frac{3}{7}+\frac{3}{5}.\frac{2}{9}-\frac{3}{5}.\frac{3}{11}\)
\(=\frac{3}{5}\left(\frac{3}{7}+\frac{2}{9}-\frac{3}{11}\right)\)
\(=\frac{3}{5}.\left(\frac{297}{693}+\frac{154}{693}-\frac{189}{693}\right)\)
\(=\frac{3}{5}.\frac{262}{693}\)
\(=\frac{262}{1155}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(-\dfrac{3}{7}\times\dfrac{15}{13}-\dfrac{3}{7}\times\dfrac{11}{13}-\dfrac{3}{7}\)
\(=-\dfrac{3}{7}\left(\dfrac{15}{13}+\dfrac{11}{13}+1\right)\)
\(=-\dfrac{3}{7}\left(\dfrac{15}{13}+\dfrac{11}{13}+\dfrac{13}{13}\right)\)
\(=-\dfrac{3}{7}\times\dfrac{39}{13}=-\dfrac{3}{7}\times3=-\dfrac{9}{7}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 1 - 2 - 3 + 4 + 5 + 6 - 7 + ... + 1996 + 1997 - 1998 - 1999 + 2000 + 2001
= ( 1 - 2 - 3 + 4 ) + ( 5 - 6 - 7 + 8 ) + ... +( 1993 - 1994 - 1995 + 1996 ) + ( 1997 - 1998 - 1999 + 2000 ) + 2001
= 0 + 0 + ... + 0 + 0 + 2001
= 2001
b, 1 - 3 + 5 -7 + ...+ 2001 - 2003 + 2005
= ( 1 -3 ) + ( 5 - 7 ) + ... + ( 2001 - 2003 ) + 2005
= -2 + (-2 )+ ... + (-2) + 2005
Có 501 số ( - 2 )
= ( - 2 ) . 501 + 2005
= -1002 + 2005
= 1003
P/s : Tham khảo ( Chép đầu bài thôi cũng sai )
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5}{11}\cdot\dfrac{3}{17}+\dfrac{5}{11}\cdot\dfrac{8}{17}=\dfrac{5}{11}\cdot\left(\dfrac{3}{17}+\dfrac{8}{17}\right)=\dfrac{5}{11}\cdot\dfrac{11}{17}=\dfrac{5}{17}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
5^4-3/100=1/20
3^3+2+1/3*13=3^5/13
5.3^7-5/5.3^5-3=1
2^15+14+13/2^13+12+11=2^6
![](https://rs.olm.vn/images/avt/0.png?1311)
Nguyễn Linh Anh, sao bạn tính giỏi thế????????????????????????????????????
`@` `\text {Ans}`
`\downarrow`
`(3^5 * 3^7)/(3^11)`
`= (3^(5+7))/(3^11)`
`= (3^12)/(3^11)`
`=3`
\(\dfrac{3^5\cdot3^7}{3^{11}}\)
\(=\dfrac{3^{5+7}}{3^{11}}\)
\(=\dfrac{3^{12}}{3^{11}}\)
\(=3^{12-11}\)
\(=3\)