Bài 1: 

1: =-5/24+16/27+3/4

=-5/24+18/24+16/27

=13/24+16/27

=117/216+128/216=245/216

2: =-1/3+1/3+6/7=6/7

3: \(=\dfrac{1}{2}-\dfrac{7}{12}+\dfrac{1}{2}=1-\dfrac{7}{12}=\dfrac{5}{12}\)

4: \(=-\dfrac{5}{8}+\dfrac{14}{25}-\dfrac{6}{10}=\dfrac{-125+112-120}{200}=\dfrac{-133}{200}\)

a) Ta có: \(\dfrac{-3}{5}x+\dfrac{-7}{4}=\dfrac{3}{10}\)

\(\Leftrightarrow\dfrac{-3}{5}x=\dfrac{3}{10}+\dfrac{7}{4}=\dfrac{41}{20}\)

\(\Leftrightarrow x=\dfrac{41}{20}:\dfrac{-3}{5}=\dfrac{41}{20}\cdot\dfrac{-5}{3}\)

hay \(x=-\dfrac{41}{12}\)

Vậy: \(x=-\dfrac{41}{12}\)

a.1/4

b.-7/144

c.25/21

d.17/7

e.80/63

f.9/7

a)1/4

b)-7/144

c)-25/21

d)17/7

e)16/63

f)9/7

Câu a:

2/3 + 1/5.10/7

= 2/3 + 2/7

= 14/21 + 6/21

= 20/21

Câu b:

2/7 + 5/7.14/25

= 2/7 + 2/5

= 10/35 + 14/25

= 24/35

Câu c:

7/12 - 27/7.1/18

= 7/12 - 3/14

= 49/84 - 18/84

= 31/84

Câu d:

3/10.(-5/6) - 1/8

= - 1/4 - 1/8

= -2/8 - 1/8

= - 3/8

Câu 1:

16 - 18|x| = - 8 - 14|x|

18|x| - 14|x| = 16 + 8

4|x| = 24

|x| = 24 : 4

|x| = 6

x = - 6 hoăc x = 6

Vậy x ∈ {-6; 6}

e) 15-3|4x +2| = 3

3|4x + 2| = 15 - 3

3|4x + 2| = 12

|4x + 2| = 12 : 3

|4x + 2| = 4

4x + 2 = -4 hoặc 4x + 2 = 4

Th1: 4x + 2 = - 4

4x = - 4 - 2

4x = - 6

x = - 6/4

x = - 3/2

Th2: 4x + 2 = 4

4x = 4 - 2

4x = 2

x = 2/4

x = 1/2

Vậy x ∈ {- 3/2; 1/2}

ban tu lam di,luoi the

bai ki vay ,

a) x= 1/4

b) x= -7/144

c) x= 25/6

d) x=17/7

e) x= 80/63

f) x= -45/14

Câu a:

4/9.x = 1/9

x = 1/9 : 4/9

x = 1/9 x 9/4

x = 1/4

vậy x = 1/4

Câu b:

x : -1/2 = 7/12

x = 7/12 x (-1/2)

x = - 7/24

Vậy x = - 7/24

Câu c:

-5/4 : x = -3/10

x = -5/4 : (-3/10)

x = -5/4 x (-10/3)

x = 25/6

Vậy x = 25/6