a) (-12). (7 - 72) - 25. (55 - 43) 

= (-12). (- 65) - 25. 12 

= 12. 65 – 12. 25

= 12. (65 - 25) 

= 12. 40 

= 480

b) (39 - 19) : (- 2) + (34 - 22). 5 

= 20 : (- 2) + 12. 5 

= - 10 + 60

= 60 - 10 

= 50.

fffff

a) 450 – ( 25 – 10) = 450 – 15

                   = 435

450 – 25 – 10 = 425 – 10

                   = 415

b) 180 : 6 : 2 = 30 : 6

                   = 15

180 : ( 6 : 2 ) = 180 : 3

                   = 60

c) 410 – (50 +30) = 410 -80

                   = 330

410 - 50 + 30 = 360 + 30

                   = 390

d) 16 x (6 : 3) = 16 x 2

                   = 32

16 x 6 : 3 = 96 : 3

                   = 32

a/ 35 – 2.1¹¹¹ + 3. 7²
= 35 - 2.1 + 3.49
= 35 - 2 + 147
= 33 + 147
= 180
 b/ 5.4³ + 2.3 – 81. 2 + 7
= 5.64 + 6 - 162 + 7
= 320 + 6 - 162 + 7
= 326 - 162 + 7
= 164 + 7
= 171 
c/ 2⁵ + 2.{12 + 2.[3.(5-2)+1]+1}+1 
= 32 + 2.{12 + 2.[3.3+1]+1}+1
= 32 + 2.{12 + 2.10+1}+1
= 32 + 2.{12 + 20 + 1}+1
= 32 + 2.{32+1}+1
= 32 + 2.33 + 1
= 32 + 66 + 1
= 98 + 1
= 99
 d/ 17.131 + 69.17
= 17 . (131+69)
= 17 . 200
= 3400
 e/ 50 – [30 - (6 - 2)² ]
= 50 - [30 - 4²]
= 50 - 14
= 36
 f/ 199 +36 + 201 + 184 + 37 
= (199+201)+(36+184)+37
= 400 + 220 + 37
= 657

25 – (20 - 10) = 25 - 10 = 15

80 – (30 + 25) = 80 - 55

a: =16692-57=16635

b: =81000+123=81123

c: =63963+2488/35=2241193/35

a: =16692-57=16635

b: =81000+123=81123

c: =63963+2488/35=2241193/35

Tính giá trị biểu thức.                           428 x 39 - 4674 chia 82

\(A=\frac{1}{30}+\frac{1}{42}+....+\frac{1}{110}+\frac{1}{132}\)

\(A=\frac{1}{5.6}+\frac{1}{6.7}+....+\frac{1}{10.11}+\frac{1}{11.12}\)

\(A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+....+\frac{1}{11}-\frac{1}{12}\)

\(A=\frac{1}{5}-\frac{1}{12}=\frac{7}{60}\)

Hình như bn ghi sai đề mk sửa cho

Ta có:\(A=\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{100}+\frac{1}{132}\)

\(\Leftrightarrow A=\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}+\frac{1}{11.12}\)

\(\Leftrightarrow A=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+....+\frac{1}{11}-\frac{1}{12}\)

\(\Leftrightarrow A=\frac{1}{5}-\frac{1}{12}\)

\(\Leftrightarrow A=\frac{7}{60}\)

a; 54 : 72 x 18 : 15

= 0,75 x 18 : 15

= 0,75 x 1,2

= 0,9 

b, 25 : 8 x 36 : 50

= (25  : 50) x (36 : 8)

= 0,5 x 4,5

= 2,25 

= 

a. = 0,75 x 18 : 15

    = 0,75  x 1,2

   = 0, 9

b. = ( 25 : 50 ) x ( 36 : 8)

= 0, 5 x 4,5

= 2, 25

a) |67| + |-9| - 12

= 67 + 9 - 12

= 76 - 12

= 64

b) 2. |56| - |-8|

= 2.56 - 8

= 112 - 8

= 104

c) |-45| - | 25| :5

= 45 - 25 : 5

= 45 - 5

= 40

d) 2. | -360| + |-72|:|-36|

= 2.360 + 72 : 36

= 720 + 2

= 722

=1/10+1/10+3/10+4/10+5/10+6/10+7/10+8/10+9/10

=1/10+45/10

=46/10=23/5

\(a,ĐK:x\ne-1;x\ne-2\\ b,A=\dfrac{\left(x-1\right)\left(x+1\right)}{\left(x+1\right)\left(x+2\right)}=\dfrac{x-1}{x+2}\\ x=2020\Leftrightarrow A=\dfrac{2019}{2022}=\dfrac{673}{674}\\ c,A=0\Leftrightarrow x-1=0\Leftrightarrow x=1\left(tm\right)\)