C=(2005x2006+2005-1)/(2004+2005x2006)=

(2005x2006+2004)/(2004+2005x2006)=1

rồi cảm ơn tôi đã làm trước khi cậu ra đáp án

\(\frac{2005.2007-1}{2004+2005.2006}\)

\(=\frac{2005.\left(2006+1\right)-1}{2004+2005.2006}\)

\(=\frac{2005.2006+2005-1}{2004+2005..2006}\)

\(=\frac{2005.2006+2004}{2004+2005.2006}\)

\(=1\)

4024035

4024034 k mik nha

A = \(\frac{2005\times2007-1}{2004+2005\times2006}=\frac{2005\times\left(2006+1\right)-1}{2004+2005\times2006}=\frac{2005\times2006+2005-1}{2004+2005\times2006}\)

\(=\frac{2005\times2006+2004}{2004+2005\times2006}=1\)

\(\frac{2005\times2007-1}{2004+2005\times2006}\)

\(=\frac{2005\times\left(2006+1\right)-1}{2004+2005\times2006}\)

\(=\frac{2005\times2006+2005\times1-1}{2004+2005\times2006}\)

\(=\frac{2005\times2006+2005-1}{2004+2005\times2006}\)

\(=\frac{2005\times2006+2004}{2004+2005\times2006}\)

\(=1\)

_Chúc bạn học tốt_

= 1 

làm bằng cách nợ hay lời 1

\(\frac{2005\times2007-1}{2004+2005\times2006}\)

=\(\frac{2005\times\left(2006+1\right)-1}{2004+2005\times2006}\)

=\(\frac{2005\times2006+2005\times1-1}{2004+2005\times2006}\)

=\(\frac{2005\times2006+2005-1}{2004+2005\times2006}\)

=\(\frac{2005\times2006+2004}{2004+2005\times2006}\)

Ta thấy tử số và mẫu số giống nhau nên kết quả của biểu thức bằng 1

Li-ke cho mik nhé!

\(\frac{2005.2007-1}{2004+2005.2006}=\frac{2005.\left(2006+1\right)-1}{2004+2005.2006}=\frac{2005.2006+2005.1-1}{2004+2005.2006}=\frac{2005.2006+2004}{2004+2005.2006}=1\)

\(\frac{2005.2007-1}{2004+2005.2006}=\frac{2005.\left(2006+1\right)-1}{2005.2006+2004}=\frac{2005.2006+2005-1}{2005.2006+2004}=\frac{2005.2006+2004}{2005.2006+2004}=1\)

?????????????????????????????????????????

  \(\dfrac{2006\times2007-8}{2005\times2007+1999}\)

= \(\dfrac{\left(2005+1\right)\times2007-8}{2005\times2007+1999}\)

= \(\dfrac{2005\times2007+2007-8}{2005\times2007+1999}\)

= \(\dfrac{2005\times2007+1999}{2005\times2007+1999}\)

= 1

Đặt Tổng trên là A

A     = 1/1.3 + 1/3.5 + 1/5.7 + .... + 1/2005.2007

2. A = 2 . ( 1/1.3 + 1/3.5 + 1/5.7 + .... + 1/2005.2007 )

2A   =  2/1.3  +  2/3.5  +  2/5.7  + ..... + 2/2005.2007

2A   =  1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 + ..... + 1/2005 - 1/2007

2A   =   1  -  1/2007

2A   =    2006/2007

 A     =  2006/2007 : 2

A      =  2006/4014

- Hok Tot - 

               \(\dfrac{1}{1\times3}+\dfrac{1}{3\times5}+\dfrac{1}{5\times7}+....+\dfrac{1}{2005\times2007}\)

=        \(\dfrac{1}{2}\left(\dfrac{1}{1}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{2005}-\dfrac{1}{2007}\right)\)

=        \(\dfrac{1}{2}\times\left(\dfrac{1}{1}-\dfrac{1}{2007}\right)\) 

=        \(\dfrac{1}{2}\times\dfrac{2006}{2007}\)

=              \(\dfrac{1003}{2007}\)

lớp 4 đã học cái này rồi hả