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9 tháng 1 2019
  1. -23-(-42:6+(3-5)2).-3=-23-(-7+4).-3=-23-9=-32
  2. -176+(-21-(42+175-(-121))).2=-176+(-21-338).2=-176+(-359).2=-176+(-718)=-894

a: 42*99-(-21)*176-35*(-12)

=42*99+21*176+35*12

=42(99+88)+35*12

=8274

b: =(1-2)+(3-4)+...+(199-200)

=(-1)+(-1)+...+(-1)

=-200

17 tháng 8 2023

1. a) 40

    b) 3

    c) 18

    d) 3

2. a) 291

    b) 37

    c) 61

    d) 284

a: \(C=\dfrac{-1}{2}:\dfrac{-2}{3}:\dfrac{-3}{4}\)

\(=\dfrac{-1}{2}\cdot\dfrac{3}{-2}\cdot\dfrac{4}{-3}\)

\(=-\dfrac{4}{4}=-1\)

b: \(D=\dfrac{-6}{5}:\dfrac{-5}{4}:\dfrac{-4}{3}\)

\(=-\dfrac{6}{5}\cdot\dfrac{4}{5}\cdot\dfrac{3}{4}\)

\(=\dfrac{-18}{25}\)

c: \(\dfrac{4}{20}+\dfrac{16}{42}+\dfrac{6}{15}+\dfrac{-3}{5}+\dfrac{2}{21}+\dfrac{-10}{21}+\dfrac{3}{20}\)

\(=\left(\dfrac{4}{20}+\dfrac{-3}{5}+\dfrac{6}{15}\right)+\left(\dfrac{16}{42}+\dfrac{2}{21}-\dfrac{10}{21}\right)+\dfrac{3}{20}\)

\(=\left(\dfrac{1}{5}-\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{8}{21}+\dfrac{2}{21}-\dfrac{10}{21}\right)+\dfrac{3}{20}\)

\(=\dfrac{3}{20}\)

d: \(\dfrac{42}{46}+\dfrac{250}{186}+\dfrac{-2121}{2323}+\dfrac{-125125}{143143}\)

\(=\dfrac{21}{23}+\dfrac{125}{93}+\dfrac{-21}{21}+\dfrac{-125}{143}\)

\(=\dfrac{125}{93}-\dfrac{125}{143}=\dfrac{6250}{13299}\)

20 tháng 1

Câu d, chỗ \(\dfrac{-21}{21}\) phải sửa thành \(\dfrac{-21}{23}\)

a: \(3^8:3^4+2^2\cdot2^3\)

=81+32

=123

b: \(3\cdot4^2-2\cdot3^2\)

\(=48-18\)

=30

3 tháng 10 2021

a, 38: 34+ 22. 23

= 38-4 + 22+3

= 3+ 25

= 81 + 32

= 113

b,  3 . 42- 2 . 32

= 3 . 16 - 2 . 9

= 48 - 18

= 30

c,  84 : 4 + 39: 37+ 50

= 84 : 4 + 32 + 1

= 84 : 4 + 9 + 1

= 21 + 9 + 1

= 31

d,  295 - ( 31 - 22 . 5)2

= 295 - ( 31 - 4 . 5 )2

= 295 - ( 31 - 20 )2

= 295 - 112

= 295 - 121

= 174

e, 500 - {5[409 - (23 . 3 - 21)2 ] + 103 } : 15

= 500 -  {5[409 - (8 . 3 - 21)2 ] + 103 } : 15

= 500 -  {5[409 - (24 - 21)2 ] + 103 } : 15

= 500 -  {5[409 - 32 ]+ 103 } : 15

= 500 - {5[409 - 9 ]+ 103 } : 15

= 500 - {5 . 400 + 1000 } : 15

= 500 - {2000 + 1000} : 15

= 500 - 3000 : 15

= 500 - 200

= 300

g, 53 . 2 - 100 : 4 + 23 . 5

= 125 . 2 - 100 : 4 + 8 . 5

= 250 - 25 + 40

= 225 + 40

= 265

h, 205 - [1200 - (42 - 2 . 3)] : 40

= 205 - [ 1200 - ( 16 - 2 . 3 )3 : 40

= 205 - [ 1200 - ( 16 - 6 ) ] : 40

= 205 - [ 1200 - 103 ] : 40

= 205 - [ 1200 - 1000 ] : 40

= 205 - 200 : 40

= 205 - 5

= 200

Đây nha bạn!!!

27 tháng 3 2021

a, \(\frac{4}{20}+\frac{16}{42}+\frac{6}{15}+\frac{-3}{5}+\frac{-10}{21}+\frac{3}{20}\)

\(=\left(\frac{4}{20}+\frac{-3}{5}+\frac{6}{15}+\frac{3}{20}\right)\)\(+\left(\frac{16}{42}+\frac{2}{21}+\frac{-10}{21}\right)\)

\(=\left(\frac{4}{20}+\frac{-12}{20}+\frac{8}{20}+\frac{3}{20}\right)\)\(+\left(\frac{8}{21}+\frac{2}{21}+\frac{-10}{21}\right)\)

\(=\frac{3}{20}\)

b,\(\frac{42}{46}+\frac{250}{186}+\frac{-2121}{2323}+\frac{-125125}{143143}\)

\(=\frac{21}{23}+\frac{125}{93}+\frac{-21}{23}+\frac{-125}{143}\)

\(=\left(\frac{21}{23}+\frac{-21}{23}\right)+\left(\frac{125}{93}+\frac{-125}{143}\right)\)

\(=\frac{6250}{13299}\)

20 tháng 10 2023

c: \(24:\left\{300:\left[350-\left(175+25\right)\right]\cdot102\right\}\)

\(=\dfrac{24}{300:\left(350-200\right)\cdot102}\)

\(=\dfrac{24}{300:150\cdot102}=\dfrac{24}{204}=\dfrac{2}{17}\)

d: \(6:2\cdot3+4\cdot79-2\cdot5\)

\(=9-10+316\)

=316-1

=315

20 tháng 10 2023

\(C)24:\left\{300:\left[350-\left(175+25\right)\right]\cdot102^0\right\}\)

\(=24:\left[300:\left(350-200\right)\cdot1\right]\)

\(=24:\left(300:150\right)\)

\(=24:2\)

\(=12\)

\(D)6^2:2\cdot3+4^2\cdot79-2^3\cdot5\)

\(=36:2\cdot3+16\cdot79-8\cdot5\)

\(=54+1264-40\)

\(=1278\)

16 tháng 12 2021

8: =>2x=210

hay x=105

7 tháng 10 2021

giúp tôi nhá

7 tháng 10 2021

a) 5(x+7) - 10 = 2^3 . 5

 5(x+7 ) -10 = 8 . 5 = 40

5(x+7) = 40 + 10 = 50

x + 7 = 50 : 5 = 10

x = 10 - 7 = 3

 

29 tháng 4 2016

a/ \(=\frac{21}{23}+\frac{125}{143}-\frac{101.21}{101.23}-\frac{1001.125}{1001.143}=0\)

b/ \(=\frac{4}{20}+\frac{8}{21}+\frac{2}{5}-\frac{3}{5}+\frac{2}{21}-\frac{10}{21}+\frac{3}{20}=\frac{7}{20}-\frac{1}{5}=\frac{4}{20}\)

c/ \(\frac{C}{2}=\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{420}=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{20.21}\)

\(\frac{C}{2}=\frac{3-2}{2.3}+\frac{4-3}{3.4}+\frac{5-4}{4.5}+...+\frac{21-20}{20.21}=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{20}-\frac{1}{21}\)

\(\frac{C}{2}=\frac{1}{2}-\frac{1}{21}=\frac{19}{42}\Rightarrow C=\frac{19}{21}\)