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10 tháng 12 2017

a)  3 1 2 .4 = 3 + 1 2 .4 = 3.4 + 1 2 .4 = 14

b)  3 1 2 : 4 = 3 + 1 2 : 4 = 3 4 + 1 8 = 7 8

4 tháng 4 2021

1,

a, \(\left(\dfrac{-4}{3}+\dfrac{1}{3}\right).\dfrac{5}{12}\)=-\(\dfrac{5}{12}\)

b, \(\dfrac{16}{5}+\left(\dfrac{-45}{14}\right):\dfrac{3}{28}\)

=\(\dfrac{-2}{15}\)

2,

a, 2x+19=25

=>x=3

b, \(-\dfrac{2}{9}x=\dfrac{1}{3}\)

=>x=\(\dfrac{-3}{2}\)

Bài 1: 

a) Ta có: \(\dfrac{-4}{3}\cdot\dfrac{5}{12}+\dfrac{1}{3}\cdot\dfrac{5}{12}\)

\(=\dfrac{5}{12}\cdot\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)\)

\(=\dfrac{-5}{12}\)

b) Ta có: \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)

\(=\dfrac{16}{5}+\left(\dfrac{4}{14}-\dfrac{49}{14}\right):\dfrac{3}{28}\)

\(=\dfrac{16}{5}+\dfrac{-45}{14}\cdot\dfrac{28}{3}\)

\(=\dfrac{16}{5}-30=\dfrac{-134}{5}\)

5 tháng 8 2017
cac ban co the ket voi mimh khong nic cua minh :huynh pham thien thu bui nguyen yen ngoc nuyen anh nguyet

HI CÁC ANH CHỊ

a: =8/20-5/20+6/20=9/20

b: =-2/5:9/10=-2/5*10/9=-20/45=-4/9

c: =7/8*4/9+1/14*14/5

=28/72+1/5

=53/90

d: =2/7(3/11+8/11)

=2/7

20 tháng 1 2023

a)

\(11\dfrac{3}{13}-\left(2\dfrac{4}{7}+5\dfrac{3}{13}\right)\)

\(=\dfrac{146}{13}-\left(\dfrac{18}{7}+\dfrac{68}{13}\right)\)

\(=\dfrac{146}{13}-\dfrac{18}{7}-\dfrac{68}{13}\)

\(=\left(\dfrac{146}{13}-\dfrac{68}{13}\right)-\dfrac{18}{7}\)

\(=6-\dfrac{18}{7}\)

\(=\dfrac{24}{7}\)

b)

\(\dfrac{2}{7}\times5\dfrac{1}{4}-\dfrac{2}{7}\times3\dfrac{1}{4}\)

\(=\dfrac{2}{7}\times\dfrac{21}{4}-\dfrac{2}{7}\times\dfrac{13}{4}\)

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

\(=\dfrac{2}{7}\times2\)

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

20 tháng 1 2023

\(a,11\dfrac{3}{13}-\left(2\dfrac{4}{7}+5\dfrac{3}{13}\right)\)

\(=\dfrac{146}{13}-\left(\dfrac{18}{7}+\dfrac{68}{13}\right)\)

\(=\dfrac{146}{13}-\dfrac{68}{13}-\dfrac{18}{7}\)

\(=6-\dfrac{18}{7}\)

\(=\dfrac{24}{7}\)

\(b,\dfrac{2}{7}\times5\dfrac{1}{4}-\dfrac{2}{7}\times3\dfrac{1}{4}\)

\(=\dfrac{2}{7}\times\dfrac{21}{4}-\dfrac{2}{7}\times\dfrac{13}{4}\)

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

\(=\dfrac{2}{7}\times2\)

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

8 tháng 7 2017

A=17/8

B=-2

C=74

20 tháng 3 2023

a) 2/9 - (1/20 + 2/9)

= 2/9 - 1/20 - 2/9

= (2/9 - 2/9) - 1/20

= 0 - 1/20

= -1/20

b) -3/14 + 2/13 + (-25/14) + (-15/13)

= (-3/14 - 25/14) + (2/13 - 15/13)

= -2 - 1

= -3

c) -3/11 + 11/8 - 3/8 + (-8/11)

= (-3/11 - 8/11) + (11/8 - 3/8)

= -1 + 1

= 0

d) 3/8 + (-1/4) - (7/12 - 1/6)

= 1/8 - 5/12

= -7/24

e) (1/3 + 12/67 + 13/41) - (79/67 - 28/41)

= 1/3 + 12/67 + 13/41 - 79/67 + 28/41

= 1/3 + (12/67 - 79/67) + (13/41 + 28/41)

= 1/3 - 1 + 1

= 1/3