Đáp án:

`649/36` 

Giải thích các bước giải:

 `27`  x  `171717/272727`  `+`  `373737/363636`  `=`

 Rút gọn Phân số ta được:

`=`  `27`  x `17/27`  `+`  `37/36` 

`=`   `17`  `+`  `37/36`  `=`  `649/36` 

a) \(\frac{2005\cdot2006-1}{2006\cdot2004+2005}\)

\(=\frac{2004\cdot2006+2006-1}{2006\cdot2004+2005}\)

\(=1\)

b) \(27\left(\frac{171717}{272727}+\frac{373737}{363636}\right)\)

\(=27\left(\frac{17}{27}+\frac{37}{36}\right)\)

\(=27\cdot\frac{17}{27}+27\cdot\frac{37}{36}\)

\(=17+\frac{9\cdot3\cdot37}{9\cdot4}\)

\(=17+27,75=44,75\)

P/s : ko biết câu b có đúng ko nữa

=27x(17/27+37/36)=27x17/27+27x37/36= 17+11/4=...

179/4 là đúng

179/4

Rút gọn phâ số ta dc:

\(=27.\frac{17}{27}+\frac{37}{36}\)

\(=17+\frac{37}{36}=\frac{649}{36}\)

\(=\frac{649}{36}\)nhé bạn

(27x1717171/272727+373737/363636)

=(27x17/27+37/36)

=17+37/26

=18  1/36

A, chờ tí nha 

B, rút gọn phân số ta được

= 27 . \(\frac{17}{27}\)- \(\frac{37}{36}\)

= 17 - \(\frac{36}{37}\)= \(\frac{649}{36}\)

tu lam

A,  2005 x 2006 - 1 / 2006 x 2004 + 2005

= \(\frac{4022030}{1}\)- \(\frac{1}{4022029}\)

ta thấy 1 x1 = 1 4022030 - 1 = 4022029 

4022030 x 4022029 = .... : 4022029 = 4022030 

=> \(\frac{4022030-}{4022029\times1}1\)= 1 

\(\frac{252525}{373737}=\frac{252525:10101}{373737:10101}=\frac{25}{37}\)

\(\frac{272727}{353535}=\frac{272727:10101}{353535:10101}=\frac{27}{35}>\frac{27}{37}>\frac{25}{37}\)

vậy \(\frac{252525}{373737}

\(\frac{252525}{373737}=\frac{25.10101}{37.10101}=\frac{25}{37}=\frac{875}{1295}\)

\(\frac{272727}{353535}=\frac{27.10101}{35.10101}=\frac{27}{35}=\frac{999}{1295}\)

Vì \(\frac{875}{1295}

\(\frac{252525}{373737}=\frac{252525:10101}{373737:10101}=\frac{25}{37};\frac{272727}{353535}=\frac{272727:10101}{353535:10101}=\frac{27}{35}\)

=>25/37<27/35

1313/1717 = ( 1313 :101)/(1717:101)=13/17

171717/191919=(171717:10101)/(191919:10101)=17/19

231231/343343=(231231:7007)/(343343:7007)=33/49

373737/494949=(373737:10101)/(494949:10101)=37/49

37/42+37/56+37/72 = 37(1/42+1/56+1/72)=37( 1/6.7 + 1/7.8 + 1/8.9 )= 37( 1/6 - 1/7 + 1/7 - 1/8 + 1/8 - 1/9)= 37( 1/6 - 1/9)= 37.1/18=37/18

B = 37/42 + 37/56 + 37/72 

B = 37/18

37/42 + 37/56 +37/72=37/24 + 37/72= 37/18