b) -1911 - ( 1234 - 1911)
c) -15 .29 + 71.(-15)
d) 156 . 72 + 28.156
Bài 1:
a) 27+46+(-79)+54+(-21)
b)-25×72+25×21-49×25
c) 35(14-23)-23(14-35)
d)-25×21+25×72+49×25
e)-1911-(1234-1911)
g)156×72+28×156
Giải:
a, 27 + 46 + (-79) + 54 + (-21)
= 27 + (46 + 54) - (79 + 21)
= 27 + 100 - 100
= 27
b, -25.72 + 25.21 - 49.25
= 25(-72 + 21 - 49)
= 25.(-100)
= -2500
c, 35(14 -23) - 23(14 - 35)
= 35.14 - 35.23 - 23.14 + 23.35
= (35.14 - 23.14) - (35.23 - 23.35)
= 14(35 - 23) - 0
= 14.12
= 168
d, -25.21 + 25.72 + 49.25
= 25(-21 + 72 + 49)
= 25.100
= 2500
e, -1911 - (1234 - 1911)
= -1911 - 1234 + 1911
= (1911 - 1911) - 1234
= -1234
g, 156.72 + 28.156
= 156(72 + 28)
= 156.100
= 15600
Chúc bạn học tốt !
-1911-(1234-1911)
156.72+28.156
32.(-39)+16.(-22)
-1945-(567-1945)
184.33+67.184
44.(-36)+22.(-28)
Tính hợp lí nhất:
1) -1911 - (1234 - 1911)
2) 156 . 72 + 28 . 156
3) 32 . (-39) + 16 . (-22)
4) -1954 - (567 - 1954)
5) 184 . 33 + 67 . 184
6) 44 . ( -36) + 22 . (-28)
(Mk cần gấp)
1) -1911 -( 1234 -1911)
= -1911 - 1234 + 1911 = -1234
2) 156.72+ 28. 156
= 156.(72+28)
= 156. 100
= 15600
3)32. (-39) + 16.(-22)
= 16.2.(-39) + 16.(-22)
= 16. (-78) + 16.(-22)
= 16.[(-78) + (-22)]
= 16. (-100)
= -1600
4) -1954 - (567 - 1954)
= -1954 - 567 + 1954
= -567
5)184. 33 + 67. 184
= 184.(33+ 67)
= 184. 100
= 18400
6) 44. (-36) + 22. (-28)
= 22.2.(-36) + 22.(-28)
= 22.(-72) + 22.(-28)
= 22. [(-72)+ (-28)]
= 22. (-100)
= -2200
1) -1911 - (1234 - 1911)
= -1911 - 1234 + 1911
= (-1911 + 1911 ) + 1234
= 0 + 1234
= 1234
2) 156 . 72 + 28 . 156
= 156 . ( 72 + 28 )
= 156 . 100
= 15600
3) 32 . (-39) + 16 . (-22)
= [ 32 . (-39) ] + [ 16 . (-22) ]
= -1248 + (-352)
= - 1600
4) -1954 - (567 - 1954)
= -1954 - 567 + 1954
= (-1954 + 1954) + 567
= 0 + 567
= 567
5) 184 . 33 + 67 . 184
= 184 . (33 + 67)
= 184 . 100
= 18400
6) 44 . ( -36) + 22 . (-28)
= [ 44 . (-36) ] + [ 22 . (-28) ]
= -1584 + (-616)
= -2200
1, -1911 - (1234 - 1911)
= -1911 - 1234 + 1911
= 1911 - 1911 - 1234
= 0 - 1234
= -1234
Bài 1: 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)
câu 1 = -68
câu 2 =-2500
câu 3=168
câu 4 =4571
câu 6=124
Bài 1: Tính một cách hợp lí:
1) 2155 - ( 174 + 2155 ) + ( -68 + 174 ) 7) -1911 - ( 1234 - 1911 )
2) -25 . 72 + 25 . 21 - 49 . 25 8) 156 . 72 + 28 . 156
3) 35 . ( 14 - 23 ) - 23 . ( 14 - 35 ) 9) 32. ( -39 ) + 16 . ( -22 )
4) 8154 - ( 674 + 8154 ) + ( -98 + 674 ) 10) -1945 - ( 567 - 1945 )
5) -25 . 21 + 25 . 72 + 49 . 25 11) 184 . 33 + 67 . 184
6) 27 . ( 13 - 16 ) - 16 . ( 13 - 27) 12) 44 . ( -36 ) + 22 . ( -28 )
1) 2155-(174+2155)+(-68+174-7)-1911-(1234-1911)
=2155-174-2155+(-68)+174-7-1911-1234+1911
=(2155-2155)+(174-174)+(1911-1911)-(68+7+1234)
= 0 + 0 + 0 - 1309
= -1309
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)
Mọi người giúp em với
1: Ta có: \(2155-\left(174+2155\right)+\left(-68+174\right)\)
\(=2155-174-2155-68+174\)
=-68
2) Ta có: \(-25\cdot72+25\cdot21-49\cdot25\)
\(=-25\cdot\left(72-21+49\right)\)
\(=-25\cdot100=-2500\)
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)
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)+21-49]
=25.(-100)
=-2500
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
-1911-(1234-1911)
-1911-(1234-1911)
= -1911-1234+1911
= [(-1911)+1911]-1234
= 0-1234
=-1234
-1911-(1234-1911)
=-1911-1234+1911
=(-1911+1911)-1234
=0-1234
=-1234
-1911(1234-1911)
-1911(1234-1911)
= -1911. (- 677)
= 1293747
-1911( 1234 - 1911)
= -1911 . (-677)
=1293747
Cách 1: \(-1911\left(1234-1911\right)\\ =-1911\cdot\left(-677\right)\\ =1293747\)
Cách 2: \(-1911\left(1234-1911\right)\\ =-1911\cdot1234-\left(-1911\right)\cdot1911\\ =-2358174-\left(-3651921\right)\\ =-2358174+3651921\\ =1293747\)