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a) \(\left(145\times99+145\right)-\left(143\times102-143\right)\)
\(=\left[145\times\left(99+1\right)\right]-\left[143\times\left(102-1\right)\right]\)
\(=\left(145\times100\right)-\left(143\times101\right)\)
\(=14500-14443\)
\(=57\)
b) \(54\times47-47\times53-20-27\)
\(=47\times\left(54-53\right)-20-27\)
\(=47-20-27\)
\(=0\)
c) \(10000-47\times72-47\times28\)
\(=10000-47\times\left(72+28\right)\)
\(=10000-47\times100\)
\(=10000-4700\)
\(=5300\)
d) \(3457-27\times48-48\times73+6543\)
\(=\left(3457+6543\right)-48\times\left(27+73\right)\)
\(=10000-48\times100\)
\(=10000-4800\)
\(=5200\)
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a) 10000 - 47 . 72 - 47 . 28
= 10000 - 47 ( 72 - 28 )
= 10000 - 47 . 44
= 10000 - 2068
= 7932
b) 3457 - 27 . 48 - 48 . 73 + 6543
= 3457 - 48 ( - 27 - 48 ) + 6543
= 3457 - 48 . ( - 75 ) + 6543
= 3457 - ( - 27 ) + 6543
= 3457 + 27 + 6543
= 10027
a, 10000-47×72-47×28
= 10000-47(72+28)
=10000-47×100
=10000-4700= 5300
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a/ = 113 x ( 54 + 45 + 1 ) = 113 x 100 = 11300
b/ = 47 x ( 54 - 53 ) - 20 - 27 = 47 - 20 - 27 = 0
c/ = 145 x ( 99 + 1 ) - 143 x ( 101 - 1 ) = 145 x 100 - 143 x 100 = 100 x ( 145 - 143 ) = 100 x 2 = 200
d/ = 1002 x 9 - 2 x 9 = 9 x ( 1002 - 2 ) = 9 x 1000 = 9000
e/ = 24 x 427 + 24 x 573 = 24 x ( 427 + 573 ) = 24 x 1000 = 24000
f/ Sửa đề bài là :
2008 x 867 + 2008 x 133 = 2008 x ( 867 + 133 ) = 2008 x 1000 = 2008000
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72:[47+(x-2)+98)=9
72:(47+68-2+x) =9
72:(113+x) =9
113+x =72:9
113+x =8
x =8-113
x =-105
Vậy x=-105
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b, 53.39 + 47.39 - 53.21 - 47.21
= 39( 53 + 47) - 21 53 + 47)
= 39.100 - 21.100
= 100(39 - 21)
= 100. 18
= 1800
bấm cho mình đúng nha ^_^
a)=78.(31+24+17)+22.72
=72.(78+22)
=72.100
=7200
b)=39.(53+47)-21.(53+47)
=100.(39-21)
=100.18
=1800
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15/10 = 1,5
24/100 = 0,24
147/1000 = 0,147
25/1000 = 0,025
47/10 = 4,7
149/10000 = 0,0149
15/10 : 1,5
24/100 : 0,24
147/1000 : 0,147
25/1000 : 0,025
47/10 : 4,7
149/10000 : 0,0149
Lời giải:
$10000-47\times 72-47\times 2$
$=10000-(47\times 72+47\times 2)$
$=10000-47\times (72+2)=10000-47\times 74=10000-3478$
$=6522$
đề bài là tính nhanh hả