Question

Tính hợp lí nhất:

1) 2155 - (174 + 2155) + (-68 + 174)

2) -25 . 72 + 25 . 21 - 49 . 25

3) 35(14 - 23) - 23(14 - 35)

4) 8154 - (674 + 8154) + (-98 + 674)

5) -25 . 21 + 25 . 72 + 49 . 25

6) 27(13 - 16) - 16(13 - 27)

7) -1911 - (1234 - 1911)

8) 156 . 72 + 28 . 156

9) 32 . (-39) + 16.(-22)

10) -1945 - ( 567 - 1945)

11) 184 . 33 + 67 . 184

12) 44 . (-36) + 22 . (-28)

( Mk cần gấp)

Answer 1

1) 2155-(174+2155)+(-68+174)

=2155-174-2155-68+174

=2155-2155+174-174-68

=0+0-68

=-68

Answer 2

2) -25.72+25.21-49.25

=25.[(-72)+21-49]

=25.(-100)

=-2500

Answer 3

3) 35(14 - 23) - 23(14 - 35)

= 35.14 - 35.23 - (23.14 - 23.35)

= 35.14 - 35.23 - 23.14 + 23.35

= (35.14 - 23.14) + (23.55 - 35.23)

= 14.(35-23) + 0

= 14.12 + 0

= 168

4) 8154 - (674 + 8154) + (-98 + 674)

= 8154 - 674 - 8154 - 98 + 674

= (8154 - 8154) + (674 - 674) - 98

= 0 + 0 - 98

= -98

5) (-25).21 + 25.72 + 49.25

= 25.[(-21) + 72 + 49]

= 25.100

= 2500

6) 27(13 - 16) - 16(13 - 27)

= 27.13 - 27.16 - (16.13 - 16.27)

= 27.13 - 27.16 - 16.13 + 16.27

= (27.13 - 16.13) + (16.27 - 27.16)

= 13.(27-16) + 0

= 13.11 + 0

= 143

7) (-1911) - (1234 - 1911)

= (-1911) - 1234 + 1911

= [(-1911) + 1911] - 1234

= 0 - 1234

= -1234

8) 156.72 + 28.156

= 156.(72+28)

= 156.100

= 15600

9) 32.(-39) + 16.(-22)

= 16.2.(-39) + 16.(-22)

= 16.(-78) + 16.(-22)

= 16.[(-78) + (-22)]

= 16.(-100)

= -1600

10) (-1945) - (567 - 1945)

= (-1945) - 567 + 1945

= [(-1945) + 1945] - 567

= 0 - 567

= -567

11) 184.33 + 67.184

= 184.(33 + 67)

= 184.100

= 18400

12) 44.(-36) + 22.(-28)

= 22.2.(-36) + 22.(-28)

= 22.(-72) + 22.(-28)

= 22.[(-72) + (-28)]

= 22.(-100)

= -2200

Answer 4

1) 2155 - (174 + 2155) + (-68 + 174)

= 2155 - 174 - 2155 - 68 + 174

= (2155 - 2155) + (-174 + 174) - 68

= 0 + 0 - 68

= -68

2) -25 . 72 + 25 . 21 - 49 . 25

= 25 . (-72) + 25.21 + 25. (-49)

= 25. [(-72) + (-49) + 21]

= 25. (-100)

= - 2500

3) 35(14 - 23) - 23(14 - 35)

= 35.14 - 23.35 - 23.14 + 23.35

= (23.35 - 23.35) + (35.14 - 23.14)

= 0 + (35-23).14

= 168

4) 8154 - (674 + 8154) + (-98 + 674)

= 8154 - 674 - 8154 - 98 + 674

= (8154 -8154 ) + (-674+674) - 98

= 0 + 0 - 98

= -98

5) -25 . 21 + 25 . 72 + 49 . 25

= 25 . (-21) + 25.72 + 25. 49

= 25. [72 + 49 + (-21)]

= 25. 100

= 2500

6) 27(13 - 16) - 16(13 - 27)

= 27.13 - 16.27 - 16.13 + 16.27

= (- 16.27 + 16.27 ) + (27.13 - 16.13 )

= 0 + 13.(27-16)

= 143