a: \(=\dfrac{3}{22}\cdot22\cdot\dfrac{3}{11}=3\cdot\dfrac{3}{11}=\dfrac{9}{11}\)

b: \(=\dfrac{5}{6}\cdot\dfrac{2}{5}=\dfrac{1}{3}\)

c: =17/21(3/5+2/5)=17/21

nhanh lên

a: \(=\dfrac{3}{22}\cdot22\cdot\dfrac{3}{11}=3\cdot\dfrac{3}{11}=\dfrac{9}{11}\)

b: \(=\dfrac{5}{6}\cdot\dfrac{2}{5}=\dfrac{1}{3}\)

c: \(=\dfrac{17}{21}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)=\dfrac{17}{21}\)

a : = \(\dfrac{3}{22}\). 22 . \(\dfrac{3}{11}\) = 3 . \(\dfrac{3}{11}\) = \(\dfrac{9}{11}\)

b : = \(\dfrac{5}{6}\). \(\dfrac{2}{5}\) = \(\dfrac{1}{3}\)

c: = \(\dfrac{17}{21}\)(\(\dfrac{3}{5}\) + \(\dfrac{2}{5}\)   ) = \(\dfrac{17}{21}\)

ban giai ho minh

ko ai bit thi thui ko tra loi thi cam

Bài 1 : Tính bằng cách thuận tiện 

A = 3/13 x 5/7 + 2/13 x 3/7

= 2/13 + 1/13 x 5/7 + 2/13 x 3/7

=  2/13 x 72/91 + 2/13 x 3/7

= 2/13 x ( 72/91 + 3/7 )

= 2/13 x  37/24

= 37/156.

B = 21/22 x 17/8 + 21/8 x 7/22

= 21/22 x 17/8 + 17/8 + 4/8 x 7/22

=  21/22 x 17/8 + 17/8 x 7/44

=  ( 21/22 + 7/44 ) x 21/22

=  31/44 x 21/22

=  651/968.

Chúc bạn học tốt!!!

1,35326087

-2/3

0

-6/29/44

-9

nha bạn