TA CÓ:

a; 1313/2121=13/21    165165/143143=165/143       424242/151515=42/15

=> 13/21 x 165/143 x 42/15=13 x 165 x 42/21 x 143 x 15=22/11=2

b,1995/1995 x 19961996/19931993 x 199319931993/199519951995

=1 x 1996/1993 x 1993/1995

=1 x 1996/1995

=1996/1995

a, 1313/2121 x 165165/143143 x 424242/151515

=13/21 x 165/143 x 13/5

=2

Trl :

bạn kia làm đúng rồi nhé 

    hk tốt nhé bạn @

a) 1313/2121 . 165165/143143 . 424242/151515

= 13/21 . 15/13 . 14/5 

= 2 

Ps: Rút gọn tới tối giản r tính dễ hơn ế. ;) 

Trloi chi tiết giúp tớ

=13/21*15/13*14/5

=5/7*14/5

=2

=\(\dfrac{13\cdot101}{21\cdot101}\)*\(\dfrac{165\cdot1001}{143\cdot1001}\)*\(\dfrac{42\cdot10101}{15\cdot10101}\)

=\(\dfrac{13}{21}\)*\(\dfrac{165}{143}\)*\(\dfrac{42}{15}\)

=\(\dfrac{13\cdot15\cdot11\cdot21\cdot2}{21\cdot13\cdot11\cdot15}\)=2

A=\(\dfrac{1313}{2121}\)*\(\dfrac{165165}{143143}\)*\(\dfrac{424242}{151515}\)

A=\(\dfrac{13}{3\cdot7}\)*\(\dfrac{3\cdot5}{13}\)*\(\dfrac{2\cdot7}{5}\)

A=\(\dfrac{13}{21}\)*\(\dfrac{15}{13}\)*\(\dfrac{14}{5}\)

A=\(\dfrac{13\cdot3\cdot5\cdot2\cdot7}{3\cdot7\cdot13\cdot5}\)

A= 2

\(\frac{1995}{1996}.\frac{19961996}{19311931}.\frac{19311931}{19951995}=\frac{1995}{1996}.\frac{1996}{1931}.\frac{1931}{1995}=1\)

\(\frac{1313}{2121}.\frac{165165}{143143}.\frac{424242}{151515}=\frac{13}{21}.\frac{165}{143}.\frac{42}{15}=\frac{1}{1}.\frac{11}{11}.\frac{2}{1}=2\)

a)=1

b)=2

ủng hộ mk nha

a) Bằng 1

b)Bằng 2

bằng 2

thank you !

bằng 2 bạn à                                                 ai tích mình sẽ tích lại