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a) 35.34 + 35.86 + 65.75 + 65.45 =
( 35 + 65 ) x ( 34 + 86 ) + ( 75 + 45 )
100 x 120 x 120
100 x 14400
1440000
\(35\cdot34+35\cdot86+65\cdot75+65\cdot45\\ =35\cdot\left(34+86\right)+65\cdot\left(75+45\right)\\ =35\cdot120+65\cdot120\\ =120\cdot\left(35+65\right)\\ =120\cdot100\\ =12000\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Xét\(3A=1\cdot2\left(3-0\right)+2\cdot3\left(4-1\right)+\cdot\cdot\cdot+99\cdot100\left(101-98\right)\)
\(3A=1\cdot2\cdot3-0\cdot1\cdot2+2\cdot3\cdot4-1\cdot2\cdot3+...+99\cdot100\cdot101-98\cdot99\cdot100\)
\(3A=99\cdot100\cdot101\)
\(\Rightarrow A=33\cdot100\cdot101=30300\)
A = 1 . 2 + 2 . 3 + 3 . 4 + ... + 99 . 100
3A = 1 . 2 . 3 + 2 . 3 . 3 + 3 . 4 . 3 + ... + 99 . 100 . 3
3A = 1 . 2 . ( 3 - 0 ) + 2 . 3 . ( 4 - 1 ) + 3 . 4 . ( 5 - 2 ) + ... + 99 . 100 . ( 101 - 98 )
3A = 1. 2 . 3 - 0 . 1 . 2 6 2 . 3 . 4 - 1 . 2 . 3 + 3 . 4 . 5 + 2 . 3 . 4 + ... + 99 . 100 . 101 - 98 . 99 . 100
3A = ( 1 . 2 . 3 - 1 . 2 . 3 ) + ( 2 . 3 . 4 - 2 . 3 . 4 ) + ... + ( 98 . 99 . 100 - 98 . 99 . 100 ) + ( 99 . 100 . 101 - 0.1 . 2 )
3A = 0 + 0 + 0 + ... + 0 + 99 . 100 . 101 - 0 . 1 . 2
3A = 99 . 100 . 101 - 0
A = \(\frac{99\cdot100\cdot101}{3}=333300\)
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a) 37.75+37.45+63.67+63.53
= 37.(75+45)+63.(67+53)
= 37.120+63.120
= 120.(37+63)
= 120.100
= 12000
b) 35.34+35.86+65.75+65.45
= 35.(34+86)+65.(75+45)
= 35.120+65.120
=120.(35+65)
= 120.100
= 12000
c) 78.31+78.24+78.17+22.72
= 78.(31+24+17)+22.72
= 78.72+22.72
= 72.(78+22)
= 72.100
= 7200
b) 35⋅34+35⋅86+65⋅75+65⋅45=35(34+86)+65(75+45)=35⋅120+65⋅120=(35+65)⋅120=100⋅120=12000
c) 78 . 31 + 78 . 24 + 78 . 17 + 22 . 72
= 78 . ( 31 + 24 + 17 ) + 22 . 72
= 78 . 72 + 22 . 72
= 72 . ( 78 + 22 )
= 72 .100
= 7200
chúc bạn học tốt ❤❤❤
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A,35*34+35*86+65*75+65*45
=35*[34+86]+65*[75+45]
=35*100+65*120
=35*100+65*100+65*20
=[35+65]*100+65*20
=10000+1300=11300
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 35× 34 +35× 86 + 65 × 75 + 65× 45
= 35× ( 34+86) + 65× (75 + 45)
= 35× 120 + 65 × 120
= 120 × ( 35 + 65)
= 120 × 100 = 12000
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
\(\Rightarrow35.\left(34+86\right)+65.\left(75+45\right)\)
\(\Rightarrow35.120+65.120\)
\(\Rightarrow120.\left(35+65\right)=120.100=12000\)
b)
\(\Leftrightarrow21.49-11.49+90.49+49.125.16\)
\(\Rightarrow49.\left(21-11+90+2000\right)\)
\(\Rightarrow49.2100=102900\)
a) 35 . 34 + 35 . 86 + 65 . 75 + 65 . 45
= 35 . ( 34 + 86 ) + 65 . ( 75 + 45 )
= 35 . 120 + 65 . 120
= ( 35 + 65 ) . 120
= 100 . 120
= 12000
![](https://rs.olm.vn/images/avt/0.png?1311)
a, 35.34 + 35.86 + 65.75 + 65.45
= 35.(34 + 86) + 65.(75 + 45)
= 35.120 + 65.120
= 120.(35+65)
= 120.100
= 12000
b, \(7.5^2-32:2^3+9\)
= 7.25 - 32:8 + 9
= 175 - 4 + 9
= 180
![](https://rs.olm.vn/images/avt/0.png?1311)
a) 35.34 + 35.86 + 65.75 + 65.45
= 35. ( 34 + 86 ) + 65 . ( 75 + 25 )
= 35 . 120 + 65 . 100
= 4200 + 6500
= 10700
b) 21.49 - 11.49 + 90.49 + 49.125.16
= 49 . ( 21-11+90) +49 .125.8.2
= 49 .100 + 49 .1000 .2
= 4900 + 49000 .2
= 4900 + 98000
= 102900
Hên xui nhé !!!
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a) \(146.53+146.48-146\)
\(=146\left(53+48-1\right)\)
\(=146.100\)
\(=14600\)
b) \(13.27+18.\left(-27\right)+105.27\)
\(=13.27+\left(-18\right).27+105.27\)
\(=27\left[13+\left(-18\right)+105\right]\)
\(=27.100\)
\(=2700\)
c) \(-124-\left(-564-24\right)-364\)
\(=-124-564+24-364\)
\(=-124+\left(-564\right)+24+\left(-364\right)\)
\(=\left[\left(-124\right)+24\right]+\left[\left(-564\right)+\left(-364\right)\right]\)
\(=\left(-100\right)+\left(-200\right)=-300\)
d) \(\left(1324+987-456\right)-\left(324-13\right)+556\)
\(=1324+987-456-324+13+556\)
\(=1324+987+\left(-456\right)+\left(-324\right)+13+556\)
\(=\left[1324+\left(-324\right)\right]+\left[987+13\right]+\left[\left(-456\right)+556\right]\)
\(=1000+1000+100=2100\)
e) \(2-4+6-8+...........-2008+2010\) (860 số hạng)
\(=\left(2-4+6-8\right)+\left(10-12+14-16\right)+...........+\left(2002-2004+2006-2008\right)\)(215 nhóm)
\(=0+0+......+0=0\)
f) \(36.28+36.82+64.69+64.41\)
\(=36\left(28+82\right)+64\left(69+41\right)\)
\(=36.110+64.110\)
\(=110\left(36+64\right)\)
\(=110.100=11000\)
g) \(35.34+35.86+65.75+65.45\)
\(=35\left(34+86\right)+65\left(75+45\right)\)
\(=35.1200+65.1200\)
\(=1200\left(35+65\right)\)
\(=1200.100=120000\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)1200
b)4905
c) Mình nghĩ là bằng 0 nếu ở thừa số thứ 2 dấu''+'' là dấu''-''
Còn nếu là dấu''+'' thì mình chịu