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a: \(2\cdot53\cdot12+4\cdot6\cdot87-3\cdot8\cdot40\)
\(=24\left(53+87-40\right)\)
=2400
b: \(5\cdot7\cdot77+7\cdot60+49\cdot25-45\cdot42\)
\(=35\cdot77+35\cdot12+49\cdot25-45\cdot42\)
\(=35\cdot89+35\left(7\cdot5-9\cdot6\right)\)
\(=35\cdot70=2450\)
a) 2.53.12+4.6.87-3.8.40
=24.53+24.87-24.40
=24.(53+87-40)
=24.100
=2400
b) 5.7.77-7.60+49.25-45.42
=5.7.77-7.60+7.7.25-45.6.7
=7.(5.77-60+7.25-6.45)
=7.230
=1610
a, 2.53.12+4.6.87-3.8.40
= 2.53.12+2.12.87-2.12.40
= 2.12.( 53+87-40)
= 24.100
= 2400
b.
5.7.77-7.60+49.25-15.42
= 5.7.7.11- 7.5.12+ 7.7.5.5- 5.3.7.6
= 7.5( 77- 12+ 35- 18)
= 35.82
= 2870
chỉ làm 2 ý được thui
53 x 39 + 47 x 39 + 53 x 21 + 47 x 21
= 39 x (53 + 47) + 21 x (53 + 47)
= 39 x 100 + 21 x 100
= 100 x (39 + 21)
= 100 x 40
= 4000
2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
= 1272 + 2088 - 960
= 3360 - 960
= 2400
5 x 7 x 77 - 7 x 60 + 49 x 25 - 15 x 42
= 2695 - 420 + 1225 - 630
= 2275 + 595
= 2870
Học tốt!!!
\(2.53.12+4.6.87-3.8.40=24.53+24.87-24.40=24.\left(53+87-40\right)=24.100=2400\)
2.53.12 + 4.6.87 - 3.8.40
= (2.12).53 + (4.6).87 - (3.8).40
= 24.53 + 24.87 - 24.40
= 24. (53 + 87 - 40)
= 24.100
= 2400
a,5.7.77-7.60+7.7.25-15.6.7
=7.385-7.60+175.7-90.7
=7.(385-60+175-90)
=7.410
=2870
a, 53 x 39 + 47 x 39 - 53 x 21 - 47 x 21
= 53 x (39-21) + 47 x (93-21)
=53 x 18 + 47 x 18
= (53 +47) x 18
= 100 x18
=1800
b,2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40
=24 x 53 + 24 x 87 - 24 x 40
=24 x (53+87-40)
=24 x 100 =2400
c,5 x 7 x 77 - 7 x 60 +49 x 25 -15 x 42.
=5 x 7 x 77 - 7 x 5 x 12 +49 x 5 x 5 - 5 x 3 x 42.
=5 x 539 - 84 x 5 +245 x 5 -5 x 126
=5 x (539 - 84 +245 -126)
=5 x 574
=2870
\(a,53\cdot39+47\cdot39-53\cdot21-47\cdot21\)
\(=39\cdot\left(53+47\right)-21\cdot\left(53+47\right)\)
\(=39\cdot100-21\cdot100\)
\(=100\cdot\left(39-21\right)=100\cdot18\)
\(=1800\)
\(b,2\cdot53\cdot12+4\cdot6\cdot87-3\cdot8\cdot40\)
\(=24\cdot53+24\cdot87-24\cdot40\)
\(=24\cdot\left(53+87-40\right)\)
\(=24\cdot100=2400\)
a) $53.39+47.39-53.21-47.21$
$=39.(53+47)-21.(53+47)$
$=(39-21).100=18.100=1800$
b) $2.53.12+4.6.87-3.8.40$
$=24.53+24.87-24.40=24.(53+87-40)=24.100=2400$
c) $5.7.77-7.60+49.25-15.42$
$=7.385-7.60+7.175-90.7$
$=7.(385-60+175-90)=7.410=2870$
\(53.39+47.39-53.21-47.21\)
\(=39(47+53)-21(47+53)\)
\(=(39-21)(47+53)\)
\(=18.100=1800\)
\(2.53.12+4.6.87-3.8.40\)
\(=24.53+24.87-24.40\)
\(=24(53+87-40)=24.100=2400\)
\(5.7.77-7.60+49.25-15.42\)
\(=385.7-7.60+7.7.25-15.6.7\)
\(=385.7-7.60+7.175-7.90\)
\(=7(385-60+175-90)=7.410=2870\)