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 x 18
=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

\(53.39+47.39-53.21-47.21\)

\(=39\left(53+47\right)-21\left(53+47\right)\)

\(=39.100-21.100=100\left(39-21\right)\)

\(=100.18=1800\)

\(2.53.12+4.6.87-3.8.40\)

\(=24.53+24.87-24.40\)

\(=24\left(53+87-40\right)=24.100=2400\)

\(5.7.77-7.60+49.25-15.42\)

\(=7.385-7.60+7.175-7.90\)

\(=7\left(385-60+175-90\right)=7.410=2870\)

53.39+47.39−53.21−47.21

=39(53+47)−21(53+47)

=39.100−21.100=100(39−21)

=100.18=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

=7.385−7.60+7.175−7.90

=7(385−60+175−90)=7.410=2870

5.77.7 - 7.60 + 49.25 - 15.42

= 5 . 7 . 11 . 7 - 7 . 60 + 7.7.25 - 15.6.7

= 7 . ( 35.11 - 60 + 7.25 - 15.6 )

= 7 . ( 385 - 60 + 175 - 90 )

= 7 . 410

= 2870

5 . 7.77 - 7.60 + 7.7.25 - 15.6.7

= 7.(5.77 - 60 + 7.25 - 15.6 )

= 7.(5.77 - 12.5 + 35.5 - 5.18 )

= 7.[5.(77 - 12 + 35 - 18)]

= 7.5.82

= 7.410

= 2870

=2870 nha

G)5x7x77-7x60+49x25-15x42 
=5x7x77-7x12x5+7x7x5x5-5x3x7x6 
= 5x7(77-12+7x5-3x6) 
=35(77-12+35-18) 
= 35x82 

=2870

giải ra hộ mk nha tính nhanh đó bạn

1, =35 x 77-35 x 12+35x35-35 x 18 suy ra =35 x(77-12+35-18)=35 x 82=2870.

2, =2014 x (100-1)=201400-2014=199386.

3,=35x12+65x12+65=12x(65+35)+65=1200+65=1265.

4.=\(\frac{13\times\left(37-1\right)}{12\times\left(37+2\right)}\)=\(\frac{13\times36}{12\times39}=\frac{13\times3\times12}{12\times3\times13}=1\)

tck nha bạn

\(5\cdot7\cdot77-7\cdot60+49\cdot25-15\cdot42\)

\(=5\cdot7\cdot77-7\cdot5\cdot12+7\cdot7\cdot5\cdot5-3\cdot5\cdot7\cdot6\)

\(=5\cdot7\left(77-12+5\cdot7-3\cdot6\right)\)

\(=35\cdot82=2\cdot5\cdot7\cdot41=10\cdot287=2870\)

không tính nhanh được :V