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Ta có:
T = \(\frac{2009\times2010+2000}{2011\times2010-2020}=\frac{2009\times2010+2010-10}{2010\times2010+2010-2020}=\frac{2010\times2010-10}{2010\times2010-10}=1\)
Vậy T = 1
2009×2010+2000/2011×2010-2020
=2009×2010+2000/2009×2010+2×2010-2020
=2009×2010+2000/2009×2010+4020-2020
=2000/4020-2020
=2000/2000
=1
K đúng cho mk nha !!!

\(=\frac{\left(2009-1\right)\cdot2009+2000}{2009\cdot\left(2009+1\right)-2018}=\frac{2009^2-9}{2009^2-9}=1\\ \)

Lời giải:
$t=\frac{2009\times 2010+2000}{2011\times 2010-2020}$
$=\frac{2010\times (2011-2)+2000}{2011\times 2010-2020}$
$=\frac{2010\times 2011-2\times 2010+2000}{2011\times 2010-2020}$
$=\frac{2010\times 2011-2020}{2011\times 2010-2020}=1$

\(\frac{1}{1.3.7}+\frac{1}{3.7.9}+\frac{1}{7.9.13}+\frac{1}{9.13.15}+\frac{1}{13.15.19}\)
\(=\frac{1}{2}\left(\frac{1}{1.3}-\frac{1}{3.7}+\frac{1}{3.7}-\frac{1}{7.9}+...+\frac{1}{13.15}-\frac{1}{15.19}\right)\)
\(=\frac{1}{2}\left(\frac{1}{1.3}-\frac{1}{15.19}\right)=\frac{47}{285}\)

\(a.200+6+\frac{3}{100}=206,03.\) .
\(b.27+\frac{4}{10}+\frac{6}{100}=27,46\) .

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{2010}-\frac{1}{2011}\)
\(=1-\frac{1}{2011}\)
\(=\frac{2010}{2011}\)
=1/1-1/2+1/2-1/3+1/3-1/4+...+1/2010-1/2011
= 1 - 1/2011
= 2010/ 2011
Đáp số: 2010/2011
Chúy ý công thức: \(\frac{1}{n\left(n+1\right)}=\frac{1}{n}-\frac{1}{n+1}\)
\(A=\frac{2009x2010+2000}{2011x2010-2020}=\frac{2009x2010+2000}{2009x2010+2x2010-2020}=\frac{2009x2010+2000}{2009x2010+4020-2020}=\frac{2000}{4020-2020}=\frac{2000}{2000}=1\)
Nhấn đúng cho mk nha!!!!!!!!!!