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35.34 + 35.86 + 65.75 + 65.45 = 35.(34 + 86) + 65.(75 + 45) = 120.35+120.65 -120.(35 + 65) = 12000
35.34+35.38+65.75+65.45
=35.(34+38)+65.(75+45)
=35.72+65.120
=2520+7800
=10320
35.34+35.38+65.75+65.45
=35(34+38)+65(75+45)
=35.72+65.120=2520+7800=10320
Giải:
\(35.34+35.38+65.75+65.45\)
\(=35\left(34+38\right)+65\left(75+45\right)\)
\(=35.72+65.120\)
\(=2520+7800\)
\(=10320\)
Chúc bạn học tốt!
Bài 1 . Tính nhanh
35 . 34 + 35 . 38 + 65 . 75 + 65 + 45
= 35 . ( 34 + 38 ) + 65 . ( 75 + 45 )
= 35 . 72 + 65 . 120
= 2 520 + 7 800
= 10 320
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
\(35\cdot34+35\cdot86+65\cdot75+65\cdot45\\ =35\cdot\left(34+86\right)+65\cdot\left(75+45\right)\\ =35\cdot120+65\cdot120\\ =120\cdot\left(35+65\right)\\ =120\cdot100\\ =12000\)
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 = \(\frac{99\cdot100\cdot101}{3}=333300\)
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 ❤❤❤