a) \(\frac{58}{19}+\frac{13}{17}+\frac{35}{43}+\frac{119}{19}+\frac{8}{43}\)

\(=\frac{13}{17}+\left(\frac{58}{19}+\frac{119}{19}\right)+\left(\frac{35}{43}+\frac{8}{43}\right)\)

\(=\frac{13}{17}+\frac{204}{19}+1\)

\(=\frac{1808}{133}\)

b) \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+\frac{13}{4}\)

\(=\frac{-5}{7}.\left(\frac{2}{11}+\frac{9}{11}\right)+\frac{13}{4}\)

\(=\frac{-5}{7}.1+\frac{13}{4}\)

\(=\frac{71}{28}\)

c) \(\frac{146}{13}-\left(\frac{21}{7}+\frac{68}{13}\right)\)

\(=\left(\frac{164}{13}-\frac{68}{13}\right)+3\)

\(=\frac{135}{13}\)

d) \(\frac{2}{7}.\frac{21}{4}-\frac{2}{7}.\frac{13}{4}\)

\(=\frac{2}{7}.\left(\frac{21}{4}-\frac{13}{4}\right)\)

\(=\frac{2}{7}.\frac{8}{4}\)

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

P/s: Mk ko chắc nữa!

b: \(=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+\dfrac{13}{4}=\dfrac{-5}{7}+\dfrac{13}{4}=\dfrac{-20+91}{28}=\dfrac{71}{28}\)

c: \(=\dfrac{146}{13}-3-\dfrac{68}{13}=6-3=3\)

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

a/ (- 2010) - (119 - 2010)

= (- 2010) - 119 + 2010

= - 119

b/ 217 + [43 + (- 217) + (- 23)]

= 217 + [43 + (-217) - 23]

= 217 + (-217) + 20

= 20

Bài 2: Tính bằng cách hợp lý nhất:

 a) (-2010) – (119 -2010)

= -2010 - 119 + 2010

= 2010 - 2010 - 119

=     0 - 119

= -119

b) 217 +[ 43 + (-217) +(-23)]

= 217 +  43 - 217 - 23

= ( 217 - 217 ) + ( 43 - 23 )

=        0            + 20

= 20

c) (18+29)+(158 -18 -29)       

= 18 + 29 + 158 - 18 - 29

= ( 18 - 18 ) + ( 29 - 29 ) + 158

=       0        +       0         + 158

= 158

d) 126 +(-20) +2004+(-106)

= 126 - 20 + 2004 - 106

= [( 126 - 20 ) - 106 ] + 2004

= [ 106 - 106 ] + 2004

=      0 + 2004

= 2004

e) (-199) +(-200) +(-201)

= -199 - 200 - 201

= -199 - 201 - 200

= - 400 - 200

= -600

f) 99 + (-100) +101   

= 99 - 100 + 101

= 99 + 101 -100

= 200 - 100

= 100

x=-590

-190 - x= -119 + 219 + 300 

-190-x = 400

-x = 400 + 190

-x = 590

=> x = -590 

Vậy...

x=-590

219-(x+1)=199

       x+1 = 219 - 199

       x+1  = 100

       x      = 100 - 1

       x      = 99

Vậy x = 99

219-1=218

Số đó lả : 218

219-(X+1) =119

        X+1=219-119

         X+1=100

         X=100-1=99

a) 500

b) 2303                

c) 537                  

d) 35000

e) 90000

f) 380

\(a,30\cdot6+30\cdot71+20\cdot30\)

=\(30\cdot\left(6+71+20\right)\)

=\(30\cdot97=2910\)

\(b,24\cdot\left(31+119\right)+76\cdot\left(29+121\right)\)

=\(24\cdot150+76\cdot150\)

=\(150\cdot\left(24+76\right)\)

=\(150\cdot100\)

=\(15000\)

\(c,87\cdot23+70\cdot87+43\cdot93\)

=\(87\cdot\left(23+87\right)+43\cdot93\)

=\(87\cdot110+3999\)

=\(9570+3999\)

=13569

a) 15 . 6 . 2 + 3 . 71 . 10 + 20 . 30 

= ( 15 . 2 ) . 6 + ( 3 . 10 ) . 71 + 20 . 30

= 30 . 6 + 30 . 71 + 20 . 30 

= 30 . ( 6 + 71 + 30 ) 

= 30 . 107

= 3210

b) 24 . 31 + 24 . 119 + 76 . 29 + 76 . 121 

= 24 . ( 31 + 119 ) + 76 . ( 29 + 121 )

= 24 . 150 + 76 . 150 

= 150 . ( 24 + 76 ) 

= 150 . 100 

= 15 000

c) 87 . 23 + 43 . 93 + 70 . 87 

= 87 . 23 + 70 . 87 + 43 . 93 

= 87 . ( 23 + 70 ) + 43 . 93 

= 87 . 93 + 43 . 93 

= 93 . ( 87 + 43 ) 

= 93 . 130 

= 12 090

a) 15 . 6 . 2 + 3 . 71 . 10 + 20 . 30

= 30 . 6 + 30 . 71 + 30 . 20

= 30 . (6 + 71 + 20) = 30 . 97 = 2910

b) 24 . 31 + 24 . 119 + 76 . 29 + 76 . 121

= 24 . (31 + 119) + 76 . (29 + 121)

= 24 . 150 + 76 . 150 = 150 . (24 + 76)

= 150 . 100

= 15000

c) 87 . 23 + 43 . 93 + 70 . 87

= 43 . 93 + 87 . (23 + 70)

= 43 . 93 + 87 . 93

= 93 . (43 + 87)

= 93 . 130

= 12090

Sửa đề: 39*40

\(A=\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{12}+...+\dfrac{1}{39}-\dfrac{1}{40}=\dfrac{1}{5}-\dfrac{1}{40}=\dfrac{7}{40}\)

\(B=\dfrac{2}{3}\left(\dfrac{1}{5\cdot8}+\dfrac{1}{8\cdot11}+...+\dfrac{1}{17\cdot20}\right)\)

\(=\dfrac{2}{3}\left(\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+...+\dfrac{1}{17}-\dfrac{1}{20}\right)\)

=2/3*3/20=2/20=1/10=4/40<A

a, 119 + 24 + 81

= ( 119 + 81 ) + 24

= 200 + 24

= 224

b, 16 . 6 . 125

= 16 . 125 . 6

= 2000 . 6

= 12000

c, 25 . 104

= 25 . 100 + 25 . 4

= 2500 + 100

= 2600

d, 12 . 19 + 12 

= 12 . 19 + 12 . 1

= 12 . ( 19 + 1 )

= 12 x 20 

= 240

e, 43 . 27 + 93 . 43 + 57 . 61 + 59 . 57

= 43 . ( 27 + 93 ) + ( 61 + 59 ) . 57

= 43 . 120 + 120 . 57

= 120 . 43 + 120 . 57

= 120 . ( 43 + 57 )

= 120 . 100

= 12000

a/ 199 + 24 + 81 

= (119+81) + 24

= 200 + 24

= 224

b/ 16 . 6 . 125

= ( 16 . 125) . 6

= 2000 . 6

= 12000

c/ 25 . 104

= 25 . ( 100 + 4 )

= 25 . 100 + 25 . 4

= 2500 + 100

= 2600

d/43 . 27 + 93 . 43 + 57 . 61 + 59 . 57

= 43 . ( 27 + 93) + 57 . ( 61+ 59)

= 43 . 130 + 57 . 130

= (43 + 57) . 130

= 100 . 130

= 1300