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Ta co:\(\frac{2008.2009+4018}{2010.2011-4020}=\frac{2008.\left(2011-2\right)+4018}{\left(2008+2\right).2011-4020}\)
\(=\frac{2008.2011-2008.2+4018}{2008.2011+2011.2-4020}=\frac{2008.2011+4018-4016}{2008.2011+4022-4020}\)
\(=\frac{2008.2011+2}{2008.2011+2}=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài làm :
Ta có :
\(A=\frac{2008.2009+4018}{2010.2011-4020}\)
\(A=\frac{2008.2009+2009.2}{2010.2011-2010.2}\)
\(A=\frac{2009.\left(2008+2\right)}{2010.\left(2011-2\right)}\)
\(A=\frac{2009.2010}{2010.2009}=1\)
Vậy A=1 .
Chúc bạn học tốt !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
\(A=\frac{2008.2009+4018}{2010.2011-4020}\)
\(A=\frac{2008.2009+2009.2}{2010.2011-2010.2}\)
\(A=\frac{2009.\left(2008+2\right)}{2010.\left(2011-2\right)}\)
\(A=\frac{2009.2010}{2010.2009}=1\)
Vậy ....
![](https://rs.olm.vn/images/avt/0.png?1311)
2008.2009+4018
=2008.2009+2009.2
=2009.(2008+2)
=2009.3000
=6027000
b.2010.2011+4020
=2010.2011+2010.2
=2010.(2011+2)
=2010.2013
=4046130
2008 x 2009 + 40 18
= 4034072 + 4018
= 4038090
2010 x 2011 + 4020
= 4042110 + 4020
= 4046130
![](https://rs.olm.vn/images/avt/0.png?1311)
( 2008 + 1009 ) . ( 2009 - 1009 ) + 4018
3017 . 1000 + 4018
3017000 + 4018
3021018
![](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)
Ta có :\(\dfrac{2008.2009+4018}{2010.2011-4020}=\dfrac{2008.2009+2009.2}{2010.2011-2010.2}\)
\(=\dfrac{2009.\left(2008+2\right)}{2010\left(2011-2\right)}=\dfrac{2009.2010}{2010.2009}=1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có:
\(\frac{1}{100.101}+\frac{1}{101.102}+...+\frac{1}{2010.2011}\)
\(=\frac{1}{100}-\frac{1}{101}+\frac{1}{101}-\frac{1}{102}+...+\frac{1}{2010}-\frac{1}{2011}\)
\(=\frac{1}{100}-\frac{1}{2011}\)
\(=\frac{1911}{201100}\)
Ta có : \(\frac{1}{100.101}\)+ \(\frac{1}{101.102}\)+.....+\(\frac{1}{2010.2011}\)
= \(\frac{1}{100}\)- \(\frac{1}{101}\)+ \(\frac{1}{101}\)- \(\frac{1}{102}\)+.....+ \(\frac{1}{2010}\)-\(\frac{1}{2011}\)
= \(\frac{1}{100}\)- \(\frac{1}{2011}\) = .... Tự tính tiếp nhé bạn
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\frac{2010.2011+4022}{2012.2013-4024}\)
\(A=\frac{2010.2011+2011.2}{2012.2013-2012.2}\)
\(A=\frac{2011.\left(2010+2\right)}{2012.\left(2013-1\right)}\)
\(A=\frac{2011.2012}{2012.2013}=\frac{2011}{2012}\)
mk nhầm r, xl bn nha
...
\(A=\frac{2011.\left(2010-2\right)}{2012.\left(2013-2\right)}\)
\(A=\frac{2011.2012}{2012.2011}=1\)
\(\frac{2008\cdot2009+4018}{2010\cdot2011-4020}=\frac{2008\cdot2009+2009\cdot2}{2010\cdot2011-2010\cdot2}=\frac{\left(2008+2\right)\cdot2009}{2010\left(2011-2\right)}=\frac{2010\cdot2009}{2010\cdot2009}=1\)
b
2008.2009 + 4018 = 2008.2009 + 2.2009 0.25
= 2009.(2008+2) = 2009.2010 0.25
2010.2011-4020 = 2010.2011-2.2010 0.25
= 2010.(2011-2) = 2010.2009 0.25
⇒2008.2009 4018
2010.2011 4020
+
−
= 1