Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 52 – 42 + 37 – 28 + 38 + 63 = (52 – 42) + (37 + 63) + (38 – 28) = 10 + 100 + 10 = 120
b) 130 + 35.19 – 9.70 – 30
= (35.19 – 9.70) + (130 – 30) = (35.19 – 9.35.2) + 100 = 35.(19 – 18) + 100 = 35 + 100 = 135
c) (11 + 13 + 15 + … + 19).(6.8 – 48) = (11+13+15+…+19).0 = 0
d) (72 – 8.9):(20+22+24 – 19 +21+23) = 0:(20+22+24 – 19 +21+23) = 0
![](https://rs.olm.vn/images/avt/0.png?1311)
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
![](https://rs.olm.vn/images/avt/0.png?1311)
1) 2155-(174+2155)+(-68+174)
=2155-174-2155-68+174
=2155-2155+174-174-68
=0+0-68
=-68
![](https://rs.olm.vn/images/avt/0.png?1311)
1: Ta có: \(2155-\left(174+2155\right)+\left(-68+174\right)\)
\(=2155-174-2155-68+174\)
=-68
2) Ta có: \(-25\cdot72+25\cdot21-49\cdot25\)
\(=-25\cdot\left(72-21+49\right)\)
\(=-25\cdot100=-2500\)
a) 21.72 - 11.72+90.72 + 49.125.16
= 21.72 - 11.72 + 90 .72 + 72.125.8.2
= 21.72-11.72+90.72+72.1000.2
=21.72-11.72+90.72+72.2000
= 72.( 21-11 + 90 + 2000)
= 72. 2100
= 49.2100
= 102 900
b) Đặt A = ( 20+21+22+23). 20.21.22.23
A = (20+21+22+23).26
A = 26+27+28+29
=> 2A = 27+28+29+210
2A-A = 210-26
A = 210-26
A = 960