2/3+5/4=8/12+15/12=23/12

15/25+6/21=31/35

35/11-2=13/11

68/17-3=1

a) \(\frac{2}{3}+\frac{5}{4}=\frac{8}{12}+\frac{15}{12}\)

                   \(=\frac{8+15}{12}=\frac{23}{12}\)

b) \(\frac{15}{25}+\frac{6}{21}=\frac{3}{5}+\frac{2}{7}\)

                          \(=\frac{21}{35}+\frac{10}{35}=\frac{31}{35}\)

c) \(\frac{35}{11}-2=\frac{35}{11}-\frac{22}{11}\)

                      \(=\frac{13}{11}\)

d) \(\frac{68}{17}-3=\frac{68}{17}-\frac{51}{17}\)

                    \(=1\)

2/3+5/4=23/12

15/25+6/21=31/35

35/11-2=13/11

68/17-3=1

a: =35/17-18/17-9/5+4/5

=1-1=0

b: =-7/19(3/17+8/11-1)

=7/19*18/187=126/3553

c: =26/15-11/15-17/3-6/13

=1-6/13-17/3

=7/13-17/3=-200/39

a) \(\frac{58}{19}+\frac{13}{17}+\frac{35}{43}+\frac{119}{19}+\frac{8}{43}\)

\(=\frac{13}{17}+\left(\frac{58}{19}+\frac{119}{19}\right)+\left(\frac{35}{43}+\frac{8}{43}\right)\)

\(=\frac{13}{17}+\frac{204}{19}+1\)

\(=\frac{1808}{133}\)

b) \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+\frac{13}{4}\)

\(=\frac{-5}{7}.\left(\frac{2}{11}+\frac{9}{11}\right)+\frac{13}{4}\)

\(=\frac{-5}{7}.1+\frac{13}{4}\)

\(=\frac{71}{28}\)

c) \(\frac{146}{13}-\left(\frac{21}{7}+\frac{68}{13}\right)\)

\(=\left(\frac{164}{13}-\frac{68}{13}\right)+3\)

\(=\frac{135}{13}\)

d) \(\frac{2}{7}.\frac{21}{4}-\frac{2}{7}.\frac{13}{4}\)

\(=\frac{2}{7}.\left(\frac{21}{4}-\frac{13}{4}\right)\)

\(=\frac{2}{7}.\frac{8}{4}\)

\(=\frac{4}{7}\)

P/s: Mk ko chắc nữa!

b: \(=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{13}{4}=\dfrac{-5}{7}+\dfrac{13}{4}=\dfrac{-20+91}{28}=\dfrac{71}{28}\)

c: \(=\dfrac{146}{13}-3-\dfrac{68}{13}=6-3=3\)

d: \(=\dfrac{2}{7}\left(\dfrac{21}{4}-\dfrac{13}{4}\right)=\dfrac{4}{7}\)

các bn lm đến đâu cx dc miễn là lm hộ mk cái ạ, ai đang lm vào nhắn tin vs mk để mk bít nha

a; \(-\dfrac{8}{3}+\dfrac{7}{5}-\dfrac{71}{15}< x< -\dfrac{13}{7}+\dfrac{19}{14}-\dfrac{7}{2}\)

              -\(\dfrac{19}{15}\) - \(\dfrac{71}{15}\) < \(x\) < -\(\dfrac{1}{2}\) - \(\dfrac{7}{2}\)

              -6 < \(x\) < -4

             vì \(x\) \(\in\) Z nên \(x\) = -5

- \(\dfrac{19}{6}+\dfrac{-15}{2}+\dfrac{11}{3}\) < \(x\) < - \(\dfrac{5}{4}\) + \(\dfrac{19}{12}\) - \(\dfrac{10}{3}\)

- \(\dfrac{32}{3}+\dfrac{11}{3}< x< \) \(\dfrac{1}{3}\) - \(\dfrac{10}{3}\)

-7 < \(x\) < - 3

Vì \(x\in\) Z nên \(x\in\) {-6;-5;-4}

a)\(\frac{7}{1}.\frac{5}{9}.\frac{11}{35}=\frac{7.5.11}{9.5.7}=\frac{11}{9}\)

b) \(\frac{3}{5}.\frac{4}{23}.\frac{5}{6}=\frac{3.2.2.5}{5.23.3.2}=\frac{2}{23}\)

c) \(\frac{5}{2}.\frac{7}{4}.\frac{2}{7}=\frac{5.7.2}{2.7.4}=\frac{5}{4}\)

d)  \(\frac{19}{23}.\frac{12}{17}.\frac{85}{24}=\frac{19.12.5.17}{23.17.12.2}=\frac{19.5}{23.2}=\frac{95}{46}\)

Tính

A. \(\frac{7}{1}x\frac{5}{9}x\frac{11}{35}=\frac{7x5x11}{1x9x35}=\frac{11}{9}\)

B. \(\frac{3}{5}x\frac{4}{23}x\frac{5}{6}=\frac{3x4x5}{5x23x6}=\frac{2}{23}\)

C. \(\frac{5}{2}x\frac{7}{4}x\frac{2}{7}=\frac{5x7x2}{2x4x7}=\frac{35}{28}\)

D. \(\frac{19}{23}x\frac{12}{17}x\frac{85}{24}=\frac{19x12x85}{23x17x24}=\frac{4845}{2346}\)

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

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

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

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

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