=500000-100000

=400000

b) 25 x 20 x 125 x 8 - 8 x 20 x 5 x 125

= 25 x 20 x 25 x 5 x 8 - 8 x 20 x 5 x 5 x 25

= 25 x 20 x 25 x 40 - 8 x 10 x 25 x 25

= 500 x 1000 - 80 x 625

= 500 000 - 50000

= 450000

 25 x 20 x 125 x 8 - 8 x 20 x 5 x 125

= 25 x 20 x 25 x 5 x 8 - 8 x 20 x 5 x 5 x 25

= 25 x 20 x 25 x 40 - 8 x 20 x 25 x 25

= 500 x 1000 - 160 x 625

= 500 000 - 100000

= 400000

A) 240 - (127 + x) = 90

⇒ 127 + x = 240 - 90 

⇒ 127 + x = 150

⇒ x = 150 - 127

⇒ x = 23

B) 65 + (5x + 20) : 2 = 125

⇒ (5x + 20) : 2 = 125 - 65

⇒ (5x + 20) : 2 = 60

⇒ 5x + 20 = 120

⇒ 5x = 120 - 20 

⇒ 5x = 100

⇒ x = 100 : 5

⇒ x = 20

C) x ϵ B(8) và 24 ≤ x <45

Mà: B(8) = { 0;8;16;24;32;40;48;...}

⇒ x ϵ { 24; 32; 40} 

\(240-\left(127+x\right)=90\)

\(127+x=150\)

\(x=23\)

\(65+\left(5x+20\right):2=125\)

\(\left(2x+20\right):2=60\)

\(2x+20=120\)

\(2x=100\)

\(x=50\)

\(x=\left\{a\in N,a\notin32,a\notin40\text{|}24< a< 45\right\}\)

b ) B = { x ϵ N* và x < 7 }

x = { 1 ; 2 ; 3 ; ... ; 6 ; 7 }

a) (125 - x) + 25 = 98

125 - x = 98 - 25

125 - x = 73

x = 125 - 73

x = 52

b) 100 : (x + 20) = 68 : 34

100 : (x + 20) = 2

x + 20 = 100 : 2

x + 20 = 50

x = 50 - 20

x = 30

c) (3x + 12) . 5 = 25 . 4 - 10

(3x + 12) . 5 = 100 - 10

(3x + 12) . 5 = 90

3x + 12 = 90 : 5

3x + 12 = 18

3x = 18 - 12

3x = 6

x = 6 : 2

x = 3

d) 210 : (2x - 3) - 20 = 10

210 : (2x - 3) = 10 + 20

210 : (2x - 3) = 30

2x - 3 = 210 : 30

2x - 3 = 70

2x = 70 + 3

2x = 73

x = 73/2

a, ( 125 - x ) + 25 = 98

⇒ 125 - x = 73

⇒ x = 52.

Vậy..

b, 100 : ( x + 20 ) = 68 : 34

⇒ 100 : ( x + 20 ) = 2

⇒ x + 20 = 50

⇒ x = 30

Vậy...

c, ( 3 . x + 12 ) . 5 = 25 . 4 - 10

⇒ ( 3 . x + 12 ) . 5 = 90

⇒ 3 .x + 12 = 18

⇒ 3x = 6

⇒ x = 2.

Vậy...

d, 210 : ( 2 .x - 3 ) - 20 = 10

⇒ ( 2 .x - 3 ) - 20 = 21

⇒ 2x - 3 = 41

⇒ 2x = 44

⇒ x = 22.

Vậy..

Cho mk chỉnh lại câu cuối:

 d, 210 : ( 2 .x - 3 ) - 20 = 10

⇒ 210 : ( 2 .x - 3 ) = 30

⇒ 2 . x - 3 = 7

⇒ 2x = 10

⇒ x = 5.

Vậy..

a) 512 x 20 x 5

= 512 x (20 x 5)

= 512 x 100 = 51 200

b) 125 x 32 x 8

= (125 x 8) x 32 

= 1000 x 32 

= 32 000

a)

512 x 20 x 5 

= 512 x (20 x 5)

= 512 x 100

= 51 200

b) 125 x 32 x 8

= 32 x (125 x 8)

= 32 x 1000

= 32 000

a

b

25 x 20 x 125 x 8 - 8 x 20 x 5 x 15

= ( 8 - 8 ) x 25 x 20 x 125 x 20 x 5 x 15

= 0 x 25 x 20 x 125 x 20 x 5 x 15

= 0 ( vì số nào nhân 0 cũng bằng 0 )

= 500\(\times\)1000\(-\)( 8\(\times\)125 ) \(\times\)( 20\(\times\)5 )

= 500\(\times\)1000\(-\)1000\(\times\)100

= 1000\(\times\)( 500\(-\)100 )

= 1000\(\times\)400

= 400000

25 x 20 x 125 x 8 - 8 x 20 x 5 x 125

= 500 x 1000 - ( 8 x 125 ) x ( 20 x 5 )

= 500000 - 1000 x 100

= 500000 - 100000

= 400000

a: =234x(45+54+1)

=234x100

=23400

b: =(8x125)x(50x20)

=1000x1000

=1000000

a = 243x(45+54+1)

=243 x 100

=24300

b = (20 x 50 ) x (8x125)

=1000x1000

=1000000

a) 234 x 45 + 54 x 234 + 234

= 234 x (45+54+1) = 234 x 100 = 23400

b) 50 x 8 x 125 x 20 = (50 x 20) x (8 x 125)

= 1000 x 1000 = 1000000