Question

(1,5 điểm) Tính giá trị của biểu thức.

a) $\dfrac{7}{2}-\left(\dfrac{3}{4}+\dfrac{1}{5}\right)$

b) $\dfrac{12}{23} . \dfrac{7}{13}+\dfrac{11}{23} . \dfrac{7}{13};$

c) $|-2|-\left(\dfrac{5}{9}-\dfrac{2}{3}\right)^2: \dfrac{4}{27}.$

Answer 1

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

= 7/2 - 19/20

= 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

= 7/13 . (12/23 + 11/23)

= 7/13 . 1

= 7/13

c) |-2| - (5/9 - 2/3)² : 4/27

= 2 - 1/81 : 4/27

= 2 - 1/12

= 23/12

Answer 2

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

= 7/2 - 19/20

= 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

= 7/13 . (12/23 + 11/23)

= 7/13 . 1

= 7/13

c) |-2| - (5/9 - 2/3)² : 4/27

= 2 - 1/81 : 4/27

= 2 - 1/12

= 23/12

Answer 3

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

=\(\dfrac{7}{2}\)-(\(\dfrac{15}{20}\)+\(\dfrac{4}{20}\))

=\(\dfrac{7}{2}\)-\(\dfrac{19}{20}\)

=\(\dfrac{70}{20}\)-\(\dfrac{19}{20}\)

\(\dfrac{51}{20}\)

b) \(\dfrac{12}{23}\).\(\dfrac{7}{13}\)+\(\dfrac{11}{23}\).\(\dfrac{7}{13}\)

=\(\dfrac{7}{13}\).(\(\dfrac{12}{23}\)+\(\dfrac{11}{23}\))

=\(\dfrac{7}{13}\).1

=\(\dfrac{7}{13}\)

c) ∣−2∣-(\(\dfrac{5}{9}\)-\(\dfrac{2}{3}\))\(^2\):\(\dfrac{4}{27}\)

= 2-(\(\dfrac{-1}{9}\))\(^2\):\(\dfrac{4}{27}\)

= 2-\(\dfrac{1}{81}\):\(\dfrac{4}{27}\)

= 2-\(\dfrac{1}{12}\)

\(\dfrac{23}{12}\)

 

Answer 4

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

b) 7/13 ( 12/23+11/23)=7/13

c) 2-1/81*27/4= 2-3/4=5/4

Answer 5

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

= 7/2 - 19/20

= 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

= 7/13 . (12/23 + 11/23)

= 7/13 . 1

= 7/13

c) |-2| - (5/9 - 2/3)² : 4/27

= 2 - 1/81 : 4/27

= 2 - 1/12

= 23/12

Answer 6

a=51/20 b=7/13 c=23/12

Answer 7

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

=7/2-(15/20+4/20)

=7/2-19/20

=70/20-19/20

=51/20

b)12/23.7/13+11/23.7/13

=7/13.(12/23+11/23)

=7/13.1

7/13

c)[-2]-(-5/9-2/3)²:4/27

=2-1/81:4/27

=2-1/81.27/4

=2-1/12

=23/12

Answer 8

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

= 7/2 - 19/20

= 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

= 7/13 . (12/23 + 11/23)

= 7/13 . 1

= 7/13

c) |-2| - (5/9 - 2/3)² : 4/27

= 2 - 1/81 : 4/27

= 2 - 1/12

= 23/12

Answer 9

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

= 7/2 - 19/20

= 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

= 7/13 . (12/23 + 11/23)

= 7/13 . 1

= 7/13

c) |-2| - (5/9 - 2/3)² : 4/27

= 2 - 1/81 : 4/27

= 2 - 1/12

= 23/12

Answer 10

a) \(\dfrac{7}{2}-\left(\dfrac{3}{4}+\dfrac{1}{5}\right)\)

= \(\dfrac{7}{2}-\dfrac{19}{20}\)

=\(\dfrac{70-19}{20}\)

=\(\dfrac{51}{20}\)

b)\(\dfrac{12}{23}\cdot\dfrac{7}{13}+\dfrac{11}{23}\cdot\dfrac{7}{13}\)

= \(\left(\dfrac{12}{13}+\dfrac{11}{23}\right)\cdot\dfrac{7}{13}\)

= \(1\cdot\dfrac{7}{13}\) = \(\dfrac{7}{13}\)

c) \(\left|-2\right|-\left(\dfrac{5}{9}-\dfrac{2}{3}\right)^2:\dfrac{4}{27}\)

= \(2-\dfrac{1}{81}:\dfrac{4}{27}\)

= \(2-\dfrac{1}{12}\) = \(\dfrac{23}{12}\)

Answer 11

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

= 7/2 - 19/20

= 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

= 7/13 . (12/23 + 11/23)

= 7/13 . 1

= 7/13

c) |-2| - (5/9 - 2/3)² : 4/27

= 2 - 1/81 : 4/27

= 2 - 1/12

= 23/12

Answer 12

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

= 7/2 - 19/20 = 70/20 - 19/20 = 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

= (12/23 + 11/23) . 7/13

= 1 . 7/13

=7/13

c) |-2| - (5/9 - 2/3)² : 4/27

= 2 - 1/81 : 4/27

= 2 - 1/12 = 23/12

Answer 13

a)7/2 - (3/4 + 1/5)             b)12/23. 7/13 + 11/23. 7/13       c)| -2 | - (5/9 - 2/3)^2 :4/27

=7/2 - 19/20                       = 7/13 . (12/23 + 11/23)            = 2 - 1/81 : 4/27

=70/20 - 19/20                   = 7/13 . 1                                  = 2 - 1/12

=51/20                               = 7/13                                       = 23/12

Answer 14

a) 51 phần 20  

b) 7 phần 13 

c) 23 phần 12 

 

 

 

Answer 15

a) 51 phần 20  

b) 7 phần 13 

c) 23 phần 12 

 

 

 

Answer 16

a) 7/2 - (3/4 + 1/5)

= 7/2 - 19/20

= 51/20

b) 12/23 . 7/13 + 11/23 . 7/13

=7/13 . (12/23 + 11/23)

=7/13 . 1

=7/13

c) I-2I - (5/9 - 2/3)² : 4/27

=2- 1/81 : 4/27

=2 - 1/12

=23/12

Answer 17

a) 7/2 - (3/4 + 1/5) = 7/2 - 19/20 = 51/20 b) 12/23 . 7/13 + 11/23 . 7/13 = 7/13 . (12/23 + 11/23) = 7/13 . 1 = 7/13 c) |-2| - (5/9 - 2/3)^2 : 4/27 = 2 - 1/81 : 4/27 = 2 - 1/12 = 23/12

Answer 18

a.51/20

b.7/13

c.971/486

Answer 19

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

=\(\dfrac{7}{2}\) - \(\dfrac{19}{20}\)

=\(\dfrac{51}{20}\)

b)\(\dfrac{12}{23}\).\(\dfrac{7}{13}\)+\(\dfrac{11}{23}\).\(\dfrac{7}{13}\)

=\(\dfrac{7}{13}\).(\(\dfrac{12}{23}\)+\(\dfrac{11}{23}\))

=\(\dfrac{7}{13}\).1 =\(\dfrac{7}{13}\)

c)\(|-2|\)-(\(\dfrac{5}{9}\)-\(\dfrac{2}{3}\))\(\div\dfrac{4}{27}\)

=2+\(\dfrac{1}{9}\).\(\dfrac{27}{4}\)

=2+\(\dfrac{3}{4}\)

=2,75 hoặc \(\dfrac{11}{4}\)

Answer 20

a)89/20

b)7/13

c)-10

Answer 21

ngon

Answer 22

Làm r nhưng bị xóa

Answer 23

a,51/20

b,7/13

c,23/12