\(\frac{31}{53}.\frac{17}{28}+\frac{31}{28}.\frac{11}{53}\)

\(=\frac{31}{53}.\frac{17}{28}+\frac{11}{28}.\frac{31}{53}\)

\(=\frac{31}{53}.\left(\frac{17}{28}+\frac{11}{28}\right)\)

\(=\frac{31}{53}.1\)

\(=\frac{31}{53}\)

\(\frac{31}{53}\times\frac{17}{28}+\frac{31}{28}\times\frac{11}{53}\)

\(=\frac{31}{53}\times\frac{17}{28}+\frac{31}{53}\times\frac{11}{28}\)

\(=\frac{31}{53}\times\left(\frac{17}{28}+\frac{11}{28}\right)\)

\(=\frac{31}{53}\times1\)

\(=\frac{31}{53}\)

\(\frac{31}{53}.\frac{17}{28}+\frac{31}{28}.\frac{11}{53}=\frac{31}{53}.\frac{17}{28}+\frac{31}{53}.\frac{11}{28}\)

 \(=\frac{31}{53}.\left(\frac{17}{28}+\frac{11}{28}\right)=\frac{31}{53}.1=\frac{31}{53}.\)

Bài 1: Ta chỉ cần bỏ ngoặc rồi cộng hai phân số để ra kết quả là số tự nhiên là xong

Bài 2:

A = \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+............+\frac{1}{2003.2004}\)

A = \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-.............-\frac{1}{2003}+\frac{1}{2003}-\frac{1}{2004}\)

A = \(1-\frac{1}{2004}\)

A = \(\frac{2004}{2004}-\frac{1}{2004}=\frac{2003}{2004}\)

Mk làm mẫu 1 bài nha 

Bài 1 :

a, = (1/4+3/4) - (5/13+8/13)+2/11

    = 1 - 1 + 2/11

    = 2/11

Tk mk nha

\(A=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2003.2004}\)

\(\Leftrightarrow A=1\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2003}-\frac{1}{2004}\right)\)

\(\Leftrightarrow A=1\left(1-\frac{1}{2004}\right)\)

\(\Leftrightarrow A=\frac{2003}{2004}\)

1,35326087

-2/3

0

-6/29/44

-9

nha bạn

bằng 22

  (28+46)+(53-28-31-46)

=53-31+28-28+46-46

=53-31

=22

[ 28 + 46] + [ 53 - 28 - 31-46]=22

NHỚ NHÉ

a) \(\dfrac{25}{37}\times\dfrac{18}{29}+\dfrac{18}{29}\times\dfrac{12}{37}\)

\(=\dfrac{18}{29}\times\left(\dfrac{25}{37}+\dfrac{12}{37}\right)\)

\(=\dfrac{18}{29}\times\dfrac{37}{37}\)

\(=\dfrac{18}{29}\times1\)

\(=\dfrac{18}{29}\)

b) \(\dfrac{31}{85}\times\dfrac{11}{19}+\dfrac{31}{85}\times\dfrac{12}{19}-\dfrac{42}{19}\times\dfrac{31}{85}\)

\(=\dfrac{31}{85}\times\left(\dfrac{11}{19}+\dfrac{12}{19}-\dfrac{42}{19}\right)\)

\(=\dfrac{31}{85}\times\dfrac{-19}{19}\)

\(=\dfrac{31}{85}\times-1\)

\(=-\dfrac{31}{85}\)

c) \(\dfrac{16}{53}:\dfrac{17}{9}-\dfrac{16}{53}:\dfrac{17}{8}\)

\(=\dfrac{16}{53}:\left(\dfrac{9}{17}-\dfrac{8}{17}\right)\)

\(=\dfrac{16}{53}:\dfrac{1}{17}\)

\(=\dfrac{16}{901}\)

c) \(\dfrac{1}{5}\times\dfrac{12}{31}\times\dfrac{4}{3}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\dfrac{12}{31}+\dfrac{19}{31}\times\dfrac{4}{15}\)

\(=\dfrac{4}{15}\times\left(\dfrac{12}{31}+\dfrac{19}{31}\right)\)

\(=\dfrac{4}{15}\times\dfrac{31}{31}\)

\(=\dfrac{4}{15}\times1\)

\(=\dfrac{4}{15}\)

a: =18/29*(25/37+12/37)

=18/29

b: =31/85(11/19+12/19-42/19)

=-31/85

c; =16/53(9/17+8/17)=16/53

d: =4/15(12/31+19/31)=4/15

=-3/31-6/17+1/25-28/31-11/17-1/5

=-1-1-4/25=-2-4/25=-54/25