=\(\dfrac{2}{3}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{2}{3}\times\dfrac{9}{9}=\dfrac{2}{3}\)

\(=\dfrac{2}{3}\times\left(\dfrac{4}{9}+\dfrac{5}{9}\right)\\ =\dfrac{2}{3}\times1=\dfrac{2}{3}\)

\(=\dfrac{2}{3}\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{2}{3}\)

2/5

2/5

= 2/5 x ( 8/7 - 1/7)

= 2/5 x 1

= 2/5

=2+8/7-2/7

=2+6/7

=20/7

14,5 x  2,7 + 2,7  x 5,5 - 2,7 x  2  x 5.

= 2,7 x 14,5 + 2,7 x 5,5 - 2,7 x 10

= 2,7 x ( 14,5 + 5,5 - 10 )

= 2,7 x 10

= 27

\(\dfrac{2}{9}+\dfrac{3}{7}+\dfrac{15}{13}+\dfrac{4}{7}-\dfrac{2}{13}+\dfrac{7}{9}\)

\(=\left(\dfrac{2}{9}+\dfrac{7}{9}\right)+\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{15}{13}-\dfrac{2}{13}\right)\)

\(=\dfrac{9}{9}+\dfrac{7}{7}+\dfrac{13}{13}=1+1+1=3\)

`2/9+3/7+15/13+4/7-2/13+7/9`

`= (2/9 + 7/9 ) + ( 3/7 + 4/7 ) + ( 15/13-2/13 ) `

`= 9/9 + 7/7 + 13/13`

`=   1 + 1 + 1 = 3`

1)a)A=(3+2)²=6²=36

B=2³+5²=8+25=33

Do 33<36

=>A>B

b)C=(3+5)³=8³=512

D=3³+5³=27+125=152

Do 512>152

=>C>D

2)2².5.[(5²+2³):11-2]-3².2

=4.5.[(25+8):11-2]-9.2

=20.(33:11-2)-18

=20.(3-2)-18

=20.1-18

=20-18

=2

giup minh cac ban

bạn ghi lại đề đi, mình ko hiểu đề

tinh nhanh (2/3x1/5+1/5):(2/3:1/5-1/5) là Tu số 1/2-21/47 là mẫu sợ đó bạn

\(\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right)-\left(5-\dfrac{1}{3}-\dfrac{6}{5}\right)-\left(6-\dfrac{7}{4}+\dfrac{3}{2}\right)\)

\(=\left(\dfrac{88-33+60}{132}\right)-\left(\dfrac{75-5-18}{15}\right)-\left(\dfrac{24-7+6}{4}\right)\)

\(=\dfrac{115}{132}-\dfrac{52}{15}-\dfrac{23}{4}\)

\(=-8\dfrac{19}{55}\)