Trả lời :

a, X + 345 = 456

    X = 456 - 345 

   X = 111

b, 3*X +15 = 45

    3*X = 45 - 15

    3*X = 30

    X = 30 : 10

   X = 3

c, 2*[ x-11] = 200

  x-11 = 200 : 2

 x-11 = 100

x = 100 + 11

x = 111

d, 16+2*X = 30

   2*X = 30 - 16

2*X = 14

X = 14 : 2

X = 7

#Study_well..

a) x + 345 = 456

x = 456 - 345

x = 111

b) 3.x + 15 = 45

3.x = 45 - 15

3.x = 30

x = 10

c) 2.(x - 11) = 200

x - 11 = 200 : 2

x - 11 = 100

x = 100 + 11

x = 111

d) 16 + 2.x = 30

2.x = 30 - 16

2.x = 14

x = 7

[200+(50-30)^2 - 456]:12

=(200+20^2-456):12

= (200 +400-456):12

=(600-456):12

=144 :12

=12

   [ 200 + ( 50 - 30 )² - 456 ] : 12

= [ 200 + 20² - 456 ] : 12

= [ 200 + 400 - 456 ] : 12

= [ 600 - 456 ] : 12 

= 144 : 12 

= 12

đáp án 12

là 12 nha

`a)25xx532xx4`

`=(25xx4)xx432`

`=432xx100=43200`

`b)456xx200-456xx100`

`=456xx(200-100)`

`=456xx100=45600`

\(a,25\times432\times4=25\times4\times432=100\times432=4320\\ b,456\times200-456\times100=456\times\left(200-100\right)=456\times100=45600\)

25 x 432 x 4

=( 25 x 4 )x 432

= 100 x 432

= 43 200

456 x 200 - 456 x 100

= 456 x ( 200 - 100)

= 456 x 100

= 45 600

(100+23).23+(200-77).77+456

= 123.23+123.77+456

= 123.(23+77)+456

= 123.100+456

= 12300+456

= 123456

  (100 + 23 ).23 + (200 - 77 ).77 + 456 

= 123 . 23 + 123 . 77 +  456

= 123 (77 + 23 ) + 456

= 123 . 100 + 456 

= 12300 + 456

= 12756 

Vừa đếm thêm 100 000 (10 000; 1000; 10; 1) vừa điền vào chỗ chấm

a) 300 000; 400 000; 500 000;600 000; 700 000; 800 000.

b) 350 000; 360 000; 370 000; 380 000; 390 000; 400 000

c) 399 000; 399 100; 399 200;399 3000; 399 400; 399 500

d) 399 940; 399 950; 399 960;399 970; 399 980; 399 990

e) 456 784; 456 785; 456 786; 456 787; 456 788; 456 789