c) Ta có: \(\dfrac{3}{5}+\dfrac{-5}{20}+\dfrac{30}{75}+\dfrac{-7}{4}\)

\(=\dfrac{3}{5}+\dfrac{2}{5}+\dfrac{-1}{4}+\dfrac{-7}{4}\)

\(=1-2=-1\)

Giải:

a)-1/12+4/3=-1/12+16/12=15/12=5/4

b)(-4/14-3/15)-(1/5-20/35-(-1)).7

=-17/35-22/35.7

=-17/35-22/5

=-171/35

c)3/5+-5/20+30/75+-7/4

=3/5+-1/4+2/5+-7/4

=(3/5+2/5)+(-1/4+-7/4)

=1+-2

=-1

d)5/6.-12/14+7/13

=-5/7+7/13

=-16/91

e)2/-9-5/-36-1/4

=-1/12-1/4

=-1/3

f)2/23+-5/12+7/18+21/23+-7/12

=(2/23+21/23)+(-5/12+-7/12)+7/18

=1+-1+7/18

=7/18

\(A=\frac{3}{7}+\frac{4}{9}+\frac{4}{7}+\frac{7}{11}\)

\(A=1+\frac{4}{9}+\frac{7}{11}\)

\(A==\frac{76}{33}\)

\(B=\frac{1}{8}+\frac{1}{12}+\frac{3}{8}+\frac{5}{12}\)

\(B=\frac{1}{2}+\frac{1}{2}\)

\(B=\frac{1}{4}\)

\(\frac{-4}{7}+\left(\frac{-2}{3}+\frac{4}{7}\right)\)

\(=\frac{-4}{7}+\frac{-2}{3}+\frac{4}{7}\)

\(=\left(\frac{-4}{7}+\frac{4}{7}\right)+\frac{-2}{3}\)

\(=0+\frac{-2}{3}=\frac{-2}{3}\)

~ Hok tốt ~

\(\frac{-3}{10}.\frac{5}{12}+\frac{-3}{10}.\frac{7}{12}+5\frac{3}{10}\)

\(=\frac{-3}{10}.\frac{5}{12}+\frac{-3}{10}.\frac{7}{12}+\frac{53}{10}\)

\(=\frac{-3}{10}.\left(\frac{5}{12}+\frac{7}{12}\right)+\frac{53}{10}\)

\(=\frac{-3}{10}.1+\frac{53}{10}\)

\(=\frac{-3}{10}+\frac{53}{10}=\frac{50}{10}=5\)

~ Hok tốt ~

a: \(=\dfrac{-5}{8}+\dfrac{7}{12}=\dfrac{-15}{24}+\dfrac{14}{24}=\dfrac{-1}{24}\)

b: \(=\dfrac{3}{4}-\dfrac{5}{6}+\dfrac{11}{12}=\dfrac{9}{12}-\dfrac{10}{12}+\dfrac{11}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)

c: \(=\dfrac{6}{36}-\dfrac{1}{36}=\dfrac{5}{36}\)

d: \(=\dfrac{5}{12}+\dfrac{5}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)

e: \(=\dfrac{-8}{56}-\dfrac{7}{56}=\dfrac{-15}{56}\)

f: \(=\dfrac{-5}{15}+\dfrac{3}{25}=\dfrac{-25}{75}+\dfrac{9}{75}=\dfrac{-16}{75}\)

Ý A là 7/-12 nhé bạn

Câu a :  

\(\dfrac{5}{12}+\dfrac{3}{4}+\dfrac{1}{3}\\ =\dfrac{5}{12}+\dfrac{9}{12}+\dfrac{4}{12}=\dfrac{3}{2}\)

câu b : 

\(\dfrac{1}{4}+\dfrac{3}{7}+\dfrac{11}{14}\\ =\dfrac{7}{28}+\dfrac{12}{28}+\dfrac{22}{28}=\dfrac{41}{28}\)

câu c : 

\(\dfrac{1}{4}+\dfrac{3}{12}+\dfrac{12}{36}\\ =\dfrac{3}{12}+\dfrac{3}{12}+\dfrac{4}{12}\\ =\dfrac{10}{12}=\dfrac{5}{6}\)

a, - 4

b, 11

Sao ko lấy máy tính cho nhanh!!

cụ thể cách làm đi

Bài 1: 

a: -8/12<0<-3/-4

b: -56/24<0<7/3

c: 4/25<1<15/13

=>-4/25>-15/13

Bài 2: 

a: =-60/45=-4/3

b: =4/15-3/2-8/5=8/30-45/30-48/30=-85/30=-17/6

Sao cx gặp bài phân số không -_-

\(a)\frac{19}{21}-\frac{1}{3}+\frac{3}{7}=\frac{19}{21}-(\frac{1}{3}+\frac{3}{7})=\frac{19}{21}-\frac{16}{21}=\frac{3}{21}\)

\(b)1+\frac{2}{3}-\frac{5}{3}=\frac{3}{3}+\frac{2}{3}-\frac{5}{3}=\frac{5}{3}-\frac{5}{3}=0\)

\(c)\frac{7}{12}+\frac{1}{3}-\frac{3}{4}=\frac{7}{12}+\frac{4}{12}-\frac{9}{12}=\frac{7+4-9}{12}=\frac{2}{12}=\frac{1}{6}\)

\(d)\frac{5}{7}-\frac{4}{7}\cdot\frac{1}{4}=\frac{5}{7}-\frac{1}{7}=\frac{4}{7}\)

\(e)\frac{7}{12}\cdot\frac{4}{3}+\frac{2}{9}=\frac{7}{9}+\frac{2}{9}=\frac{9}{9}=1\)

A. \(\frac{19}{21}-\frac{1}{3}+\frac{3}{7}=\frac{4}{7}+\frac{3}{7}=\frac{7}{7}=1\)

B. \(1+\frac{2}{3}-\frac{5}{3}=\frac{5}{3}-\frac{5}{3}=0\)

C. \(\frac{7}{12}+\frac{1}{3}-\frac{3}{4}=\frac{11}{12}-\frac{3}{4}=\frac{1}{6}\)

D. \(\frac{5}{7}-\frac{4}{7}\times\frac{1}{4}=\frac{5}{7}-\frac{1}{7}=\frac{4}{7}\)

E. \(\frac{7}{12}\times\frac{4}{3}+\frac{2}{9}=\frac{7}{9}+\frac{2}{9}=\frac{9}{9}=1\)

                       \(Linh\)\(Yukiko\)                          

a, -7

b, -10

c, 11

d,1

Lời giải:
a. $=9+5-21=14-21=-7$

b. $=2-12=-10$

c. $=8-(-3)=8+3=11$

d. $=(-4)-(-5)=-4+5=1$

a) 

Do `3/2 > 1; 4/3 > 1; 7/6 > 1`

`=> 3/2 + 4/3 + 7/6 > 1+1+1`

`=> 3/2 + 4/3 + 7/6 > 3`

b) 

Do `4/7 < 1; 5/12 <1; 84/87 < 1`

`=> 4/7 + 5/12 + 84/87 < 1+1+1`

`=> 4/7 + 5/12 + 84/87 < 3`