39 . 8 + 60 . 2 + 21 . 8 tinh nhanh
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53x39+47x39-53x21-47x21
=39x ( 53+47) - 21x(53+47)
=39 x100 - 21x100
= 100x(39-21)
=100x18
=1800
2x53x12 +4x6x87 - 3x8x40
= (2x12)x53 + (4x16)x87 - (3x8) x40
= 24x53 + 24x87 + 24x40
= 24( 53+87+40)
= 24x180
=4320
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39 . 8 + 60 . 2 + 21 . 8
= 8 .( 39 + 21 ) + 60 . 2
= 8 . 60 + 60 . 2
= 60 . ( 8 + 2 )
= 60 . 10
= 600
Hk tốt
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=8 . ( 39 + 21)+ 60 . 2 BAN NGU VAI CA DAI
MINH CUNG HOC LOP 6A VA EM HO MINH LOP 6C EM MINH DANG VIET BAI NAI
CON NGU1 BAN TE GI
=8.60 + 60. 2
=(8+ 2) .60
=10.60
=600
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\(\frac{7}{13}.\left(\frac{7}{12}\right)-\frac{5}{12}.\left(\frac{21}{39}\right)+\frac{49}{91}.\left(\frac{8}{5}\right)=\frac{7}{13}.\left(\frac{7}{12}\right)-\frac{5}{12}.\left(\frac{7}{13}\right)+\frac{7}{13}.\left(\frac{8}{5}\right)=\frac{7}{13}.\left(\frac{7}{15}-\frac{5}{12}+\frac{8}{5}\right)=\frac{7}{13}.\left(\frac{33}{20}\right)=\frac{261}{260}\)
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a, 39 . 8 + 60 . 2 + 21 . 8
= 39 . 8 + 15 . 4 . 2 + 21 . 8
= 39 . 8 + 15 . 8 + 21 . 8
= 8 . ( 39 + 15 + 21 )
= 8 . 75
= 600
b, 12 . 53 + 53 . 172 - 53 . 84
= 53 . ( 12 + 172 - 84 )
= 53 . 100
= 5300
c, 35 . 34 + 35 . 86 + 65 . 75 + 65. 67 + 65.45
= 35 . ( 34 + 86 ) + 65 . ( 75 + 67 + 45 )
= 35 . 120 + 65 . 187
= 4200 + 12155
= 16355
d, 36 . 28 + 36 . 82 + 64 . 69 + 64 . 41
= 36 . ( 28 + 82 ) + 64 . ( 69 + 41 )
= 36 . 110 + 64 . 110
= 110 . ( 36 + 64 )
= 110 . 100
= 11000
a, 39 . 8 + 60 . 2 + 21 . 8
= 39 . 8 + 15 . 4 . 2 + 21 . 8
= 39 . 8 + 15 . 8 + 21 . 8
= 8 . ( 39 + 15 + 21 )
= 8 . 75
= 600
b, 12 . 53 + 53 . 172 - 53 . 84
= 53 . ( 12 + 172 - 84 )
= 53 . 100
= 5300
c, 35 . 34 + 35 . 86 + 65 . 75 + 65. 67 + 65.45
= 35 . ( 34 + 86 ) + 65 . ( 75 + 67 + 45 )
= 35 . 120 + 65 . 187
= 4200 + 12155
= 16355
d, 36 . 28 + 36 . 82 + 64 . 69 + 64 . 41
= 36 . ( 28 + 82 ) + 64 . ( 69 + 41 )
= 36 . 110 + 64 . 110
= 110 . ( 36 + 64 )
= 110 . 100
= 11000
![](https://rs.olm.vn/images/avt/0.png?1311)
Bài làm :
\(a,35.34+35.38+65.75+65.45\)
\(=35.\left(34+38\right)+65.\left(74+45\right)\)
\(=35.72+65.120\)
\(=2520+780\)
\(=10320\)
\(b,39.8+60.2+21.8\)
\(=\left(39+21\right).8+60.2\)
\(=60.8+60.2\)
\(=60.\left(8+2\right)\)
\(=60.10=600\)
\(c,36.28+36.82+64.69+64.4\)
\(=36.\left(28+82\right)+64.\left(69+4\right)\)
\(=36.110+64.73\)
\(=3960+4672\)
\(=8632\)
\(d,123.1001\)
\(=123123\)
Học tốt
\(=8\cdot\left(39+21\right)+60\cdot2\)
\(=8\cdot60+60\cdot2=60\cdot\left(8+2\right)\)
\(=60\cdot10=600\)
~TK MK NHA. GIÚP MK LÊN 200 ĐIỂM CÁC BẠN NHÉ. ~
\(39.8+60.2+21.8=8.\left(39+21\right)+60.2\)
\(=8.60+60.2\)
\(=60.\left(8+2\right)\)
\(=60.10=6.10.10\)
\(=6.10^2=6.100=600\)