\(\text{1.(15+37)+(52-17-37)}\\ =15+37+52-17-37\\ =\left(15+52-17\right)+\left(37-37\right)\\ =50+0=50\)

\(\text{2.(21-32)-(-12+32)}\\ =21-32+12-32\\ =\left(21+12\right)+\left(-32-32\right)\\ =33+-64=-31\)

\(1,=15+37+52-17-37=50\)

\(2,=21-32+12-32=-40\)

( 18+29 ) + ( 158-28-18) 

=18+29+158-28-18

=29 + ( 18-18) + ( 158-28)

=29+0+130=159

(13-135+49)-(13+49)

=13-135+49-13-49

=(13-13)+(49-49)-135

=0+0+(-135)

=-135

3.20

a) (-28) + (-35) – 92 + (-82)

= -28 – 35 – 92 – 82 

= - (28 + 35 + 92 + 82)

= - [(28 + 82) + (35 + 92)]

= - (110 + 127)

= - 237.

b) 15 – (-38) + (-55) – (+47)

= 15 + 38 – 55 – 47

= 53 – 55 – 47

= - (55 – 53) – 47

= - 2 – 47

= - (2 + 47)

= - 49

Bài 3.20:

a: =-28-35-92-82

=-110-127

=-237

b: =15+38-55-47

=-40-47+38

=-2-47

=-49

Bài 3.21:

a: =62-81-12+59-9=50+50-81=19

b: =39-13-62-39=-75

3.21

a) (62 - 81) – (12 – 59 + 9)

= 62 – 81 – 12 + 59 – 9

= (62 – 12) – (81 + 9) + 59

= 50 – 90 + 59

= - (90 – 50) + 59

= - 40 + 59

= 59 – 40

= 19

b) 39 + (13 – 26) – (62 + 39)

= 39 + 13 – 26 – 62 – 39

= (39 – 39) – (26 + 62) + 13

= 0 – 88 + 13

= - 88 + 13

= - (88 – 13)

= - 75.

\(\text{( -12 ) + ( -13 ) + 36 + ( - 11 )}\)

\(=\left[\left(-12\right)+\left(-13\right)+\left(-11\right)\right]+36\)

\(=\left(-36\right)+36\)

\(=0\)

\(\text{- 16 + 24 + 16 _ 34}\)

\(=\left(-16+16\right)+\left(24-34\right)\)

\(=0+\left(-10\right)\)

\(=-10\)

\(\text{25 + 37 _ 48 _ 25_ 37}\)

\(=\left(25-25\right)+\left(37-37\right)-48\)

\(=0+0-48\)

\(=-48\)

\(\text{2575 + 37 _ 2576 _ 29}\)

\(=\left(2575-2576\right)+\left(37-29\right)\)

\(=\left(-1\right)+8\)

\(=7\)

\(\text{34 + 35 + 36 + 37 _ 14 _ 15 _ 16 _ 17}\)

\(=\left(34-14\right)+\left(35-15\right)+\left(36-16\right)+\left(37-17\right)\)

\(=10+10+10+10\)

\(=40\)

\(\text{( 27 + 514 ) _ ( 486 _ 73 )}\)

\(=27+514-486+73\)

\(=\left(27+73\right)+\left(514-486\right)\)

\(=100+28\)

\(=128\)

chúc bạn học tốt

Bài 1: tính hợp lí:

( -12 ) + ( -13 ) + 36 + ( - 11 )

= [ - 12 + ( - 13 ) + ( - 11 ) ] + 36

= ( - 36 ) + 36

= 0

- 16 + 24 + 16 - 34

= ( - 16 + 16 ) + ( 24 - 34 )

= 0 + ( - 10 )

= - 10

25 + 37 - 48 - 25 - 37

= ( 25 - 25 ) + ( 37 - 37 ) - 48

= 0 + 0 - 48

= - 48

2575 + 37  - 2576 -  29

= ( 2575 - 2576 ) + ( 37 - 29 )

= - 1 + 8

= 7

34 + 35 + 36 + 37  - 14 - 15 - 16 - 17

= ( 34 - 14 ) + ( 35 - 15 ) + ( 36 - 16 ) + ( 37 - 17 )

= 20 + 20 + 20 + 20

= 20 x 4

= 80

Bài 2:  bỏ dấu ngoặc rồi tính:

( 27 + 514 )  -  ( 486  - 73 )

= 27 + 514 - 486 + 73

= ( 27 + 73 ) + ( 514 - 486 )

= 100 + 28

= 128

Bài 3.21:

b: =28+19-28-32+57

=76-32

=44

|25 - 24 -10| - (28 - 30 + 4)
= |1 - 10| - (-2 + 4)
= |-9| - 2
= 9 - 2
= 7
-(-73) + (44 - 94 + 27) + 94
= 73 + (-50 + 27) + 94
= 73 + (-23) + 94
= 73 - 23 + 94
= 50 + 94
= 144
(-33 + 108 - 75) - (108 + 25)
= (75 - 75) - 133
= 0 - 133
= -133
120 - (-2 + 120 - 18) - 92
= 120 - (118 - 18) - 92
= 120 - 100 - 92
= 20 - 92
= -72

a) = 29 +37 + 13 +10 - 37 - 13

= 39

b) 79 +32 - 35 - 69 - 12 +75

= 70

a) 29+37+13+10-37-13

=(37-37)+(13-13)+29+10

=0+0+29+10

=39

a) (29 + 37 + 13) + (10 - 37 - 13)

= 29 + 37 + 13 + 10 - 37 - 13

= 39

b) (79 + 32 - 35) - (69 + 12 - 75)

= 79 + 32 - 35 - 69 - 12 + 75

= 70

Bài 1:

1: =15+37+52-37-17=52-2=50

2: =38-42+14-25+27+15=62-42+29=20+29=49

Bài 1: Bỏ ngoặc rồi tính

3) (21-32) - (-12+32)=21-32-(-12)-32=21-32+12-32=-31

4) (12+21) - (23-21+10)=12+21-23+21-10=21

5) (57-725) - (605-53)=57-725-605+53=-1220

6) (55+45+15) - (15-55+45)=55+45+15-15+55-45=55+55=110

Bài 2: Tính các tổng sau một cách hợp lí

1) (-37) + 14 + 26 + 37=(-37+37)+(14+26)=0+40=40

2) (-24) +6 + 10 + 24=(-24+24)+(6+10)=0+16=16

3) 15 + 23 + (-25) + (-23)=(15-25)+(23-23)=-10+0=-10

4) 60 + 33 + (-50) + (-33)=(60-50)+(33-33)=10+0=10

5) (-16) + (-209) + (-14) + 209=(-16-14)+(-209+209)=-30+0=-30

6) (-12) + (-13) + 36 + (-11)=(-11-12-13)+36=-36+36=0

=15+37+52-37-17 =(37-37)+52+15-17 =0+52+15-17 =67-17 =50

(38 – 42 + 14) – (25 – 27 – 15) =38-42+14-25+27+15 =27 c. -(21 – 32) – (-12 + 32) =-21+32+12-32 =-9 d. -(12 + 21 – 23) - (23 – 21 + 10) =-12-21+23-23+21-10 =-22 e. (57 – 725) – (605 – 53) =57-725-605+53 =-1220 f. (55 + 45 + 15) – (15 – 55 + 45) =55+45+15-15+55-45 =110

1) $(-35)\cdot18+28\cdot35$

$=35\cdot(-18)+28\cdot35$

$=35\cdot(-18+28)$

$=35\cdot10$

$=350$

2) $53\cdot29-47\cdot(-29)$

$=53\cdot29-47\cdot(-1)\cdot29$

$=53\cdot29+47\cdot29$

$=29\cdot(53+47)$

$=29\cdot100$

$=2900$

3) $125\cdot(-24)+24\cdot225$

$=(-125)\cdot24+24\cdot225$

$=24\cdot(-125+225)$

$=24\cdot100$

$=2400$

4) $26\cdot(-121)-121\cdot(-36)$

$=-121\cdot[26+(-36)]$

$=-121\cdot(26-36)$

$=-121\cdot(-10)$

$=121\cdot10$

$=1210$

5) $65\cdot(-25)+25\cdot(-23)$

$=-65\cdot25+25\cdot(-23)$

$=25\cdot(-65-23)$

$=25\cdot(-88)$

$=-2200$

6) $237\cdot(-26)+26\cdot137$

$=-237\cdot26+26\cdot137$

$=26\cdot(-237+137)$

$=26\cdot(-100)$

$=-2600$

7) $30\cdot(-125)+25\cdot30$

$=30\cdot(-125+25)$

$=30\cdot(-100)$

$=-3000$

8) $(-37)\cdot69+(-31)\cdot37$

$=37\cdot(-69)+37\cdot(-31)$

$=37\cdot(-69-31)$

$=37\cdot(-100)$

$=-3700$

9) $31\cdot72-31\cdot70-31\cdot2$

$=31\cdot(72-70-2)$

$=31\cdot(2-2)$

$=31\cdot0$

$=0$

10) $(-12)\cdot47+(-12)\cdot52+(-12)$

$=-12\cdot(47+52+1)$

$=-12\cdot100$

$=-1200$

$\text{#}Toru$