`15*37*4+120*21+21*5*12`

`=60*37+60*2*21+60*21`

`=60(37+42+21)`

`=60*100`

`=6000`

The topic is too difficult to understand

15 x 37 x 4 + 120 x 21 + 21 x 5 x 12 = 6000

15 . 37  .4 + 120 . 21 + 21 . 5 . 12
⇒( 15 . 4 ) . 37 + 60 . 2 . 21 + ( 12 . 5 ) .21
⇒60 . 37 + 60 . 42 + 60 . 21
⇒60 . ( 37 + 42 + 21 )
⇒60 . 100
⇒6 000
 

5.3.37.4+5.24.21+21.5.12

= 5.(3.37.4+24.21+21.12)

= 5.1200

= 6000

= ( 37 - 15 ) .4 ( vì ở phép nào cũng có số 21 ) + 120 .21 + 21 . 5 . 12

= 21 . 4 + 120 . 21 + 21 . 5.12

= 21 . ( 4 + 120 + 12 )

= 21. 136

= 2 856

mk nghĩ thế

=(15.4).37+60.2.21+(12.5).21

=60.37+60.42+60.21

=60.(37+42+21)

=60.100

=6000

= 15 . 37 . 4 + 15 . 8 + 3 . 7 + 3 .7 . 5 . 12

= 15 . 37 . 4 + 15 . 8 + 3 . 7 + 15 . 7 . 12

= 15 . (37 . 4 + 8 + 3 . 7 + 7 . 12)

= 15 . 261

= 3915

  tick đúng cho tớ nhé ! 

15.37.4 + 120.21 + 21.5.12 = 15.4.37 + 21.2.60 + 5.12.21 = 60.37 + 42.60 + 60.21 = 60.(37 + 42 + 21) = 60.100 = 6000

a) \(\text{13 x 58 x 4 + 32 x 26 x 2 + 52 x 10 }\)

\(\text{=(13 x 4 ) x 58 + 32 x 13 x 2 x 2 + 13 x 4 x 10}\)

\(\text{= ( 13 x 4 ) x 58 + 32 x ( 13 x 2 x 2 ) + ( 13 x 4 ) x 10 }\)

\(\text{= 52 x 58 + 32 x 52 + 52 x 10}\)

\(\text{=52 x ( 58 + 32 + 10 )}\)

\(\text{=52 x 100 = 5200}\)

b) \(\text{14 x 35 x 5 + 10 x 25 x 7 + 20 x 70 x 2}\)

\(\text{= ( 14 x 5 ) x 35 + (10 x 7 ) x 25 + 20 x 70 x 2 }\)

\(\text{= 70 x 35 + 70 x 25 + 20 x 2 x 70 }\)

\(\text{= 70 x ( 35 + 25 + 40 )}\)

\(\text{= 70 x 100 = 7000 }\)

e) \(\text{5.3.37.4+5.24.21+21.5.12}\)

\(\text{= 5.(3.37.4+24.21+21.12)}\)

\(\text{= 5.1200}\)

\(=6000\)

a) \(13.58.4+32.26.2+52.10\)

\(=52.58+32.52+52.10\)

\(=52.\left(58+32+10\right)\)

\(=52.100=5200\)

b) \(14.35.5+10.25.7+20.70\)

\(=7.5.35.2+10.7.25+20.70\)

\(=35.70+70.25+20.70\)

\(=70\left(35+25+20\right)\)

\(=70.80=5600\)

c) \(...=15\left(27+18+6+23+12\right)\)

\(=15\left(27+23+18+12+6\right)\)

\(=15\left(50+30+6\right)=15.86=1290\)

d) \(...=53\left(51+4+49+96+1\right)\)

\(=53\left(51+49+4+96+1\right)\)

\(=53\left(100+100+1\right)=53.201=10653\)

e) \(15.37.4+120.21+21.5.12\)

\(=15.4.37+60.2.21+21.60\)

\(=60.37+60.42+21.60\)

\(=60.\left(37+42+21\right)=60.100=6000\)

1365 x 89 - 89 x 365 = 89 x (1365 - 365) = 89 x 1000 = 89000

13 x 58 x 4 + 32 x 26 x 2 + 52 x 10 = 52 x 58 + 32 x 52 + 52 x 10 = 52 x (58 + 32+  10) = 52 x 100 = 5200

15 x 37 x 4 + 120 x 21 + 21 x 5 x 12 = 60 x 37 + 60 x 2 x 21 + 21 x 60 = 60 x (37 + 2 x 21 + 21) = 60 x 100 =6000