\(a)5^3-\left(200-x\right)=10^2\)

\(\Leftrightarrow125-\left(200-x\right)=100\)

\(\Leftrightarrow200-x=125-100\)

\(\Leftrightarrow200-x=25\)

\(\Leftrightarrow x=200-25\)

\(\Leftrightarrow x=175\)

BN VT CÓ DẤU IK MIK KO HIÊU CHO LẮM

HT NHA

@SAKURA

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  4,14 : 3,14 + 5,37 : 3,17 - 3 

= (4,14 + 5,37):3,17 - 3

= 9,51 : 3,17  -3

=  3 - 3

= 0 

nha bạn chúc bạn học tốt

4,14 : 3,14 + 5,37 : 3,17 - 3

= ( 4,14 + 5,37 ) : 3,17 - 3

= 9,51 : 3,17 - 3

= 3 - 3 

= 0

Tổng số nguyên của 3 bn ấy là:

\(\text{( 11 + 3 + 2 ) : 2 = 8}\)

Số nguyên mà Nam chọn là:

\(\text{8 - 3 = 5}\)

\(A=\frac{1}{1.5}+\frac{1}{5.9}+...+\frac{1}{17.21}\)

\(\Rightarrow4A=\frac{4}{1.5}+\frac{4}{5.9}+...+\frac{4}{17.21}\)

\(\Rightarrow4A=\frac{5-1}{1.5}+\frac{9-5}{5.9}+...+\frac{21-17}{17.21}\)

\(\Rightarrow4A=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{17}-\frac{1}{21}\)

\(\Rightarrow4A=1-\frac{1}{21}\Rightarrow4A=\frac{20}{21}\)

\(A=\frac{20}{21}:4=\frac{5}{21}\)

\(A=\frac{1}{1.5}+\frac{1}{5.9}+...+\frac{1}{17.21}\)

\(=\frac{1}{4}\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+...+\frac{1}{17}-\frac{1}{21}\right)\)

\(=\frac{1}{4}\left(1-\frac{1}{21}\right)=\frac{1}{4}.\frac{20}{21}=\frac{20}{84}=\frac{5}{21}\)

a)   ( 2600 + 6400) - 3x = 1200

=>  3x   =  9000 - 1200

=> 3x    = 7800

=>  x    =  7800 : 3

=>   x    = 2600

 Vậy x = 2600

b)   ( 1750 + 1250 ) - 5x = 2750

=>   5x  =    3000 - 2750

=> 5x    =  250

=>  x  =  250 : 5

=>  x  =  50

Vậy x  = 50

c)     [  ( 4x + 28 ).3 + 55 ] : 5 = 35

=>     [  ( 4x + 28 ).3 + 55 ]  = 35 .5

=>      [  ( 4x + 28 ).3 + 55 ]   = 175

=>      ( 4x + 28 ).3 + 55    = 175

=>       ( 4x + 28 ).3   = 175  - 55

=>         ( 4x + 28 ).3  = 120

=>          4x + 28   = 120 : 3 

=>         4x + 28   =  40 

=>        4x     = 40 - 28 

=>       4x       =  12

=>         x       = 3

 Vậy x = 3

a, (2600+6400) - 3.x= 1200

9000-3.x= 1200

3.x= 9000-1200

3.x= 7800

x= 7800 : 3

x= 2600

b, (1750+1250)-5.x=2750

3000-5.x= 2750

5.x= 3000-2750

5.x= 250

x= 250 : 5

x= 50

c, [(4x+28).3+55] :5= 35

(4x+28).3+55= 35.5

(4x+28).3+55= 175

(4x+28).3= 175-55

(4x+28).3= 120

4x+28= 120:3

4x+28= 40

4x= 40-28

4x= 12

x= 12:4

x= 3

d, 151-2(x-6)= 2227:17

151-2(x-6)= 131

2(x-6)= 151-131

2(x-6)= 20

x-6= 20: 2

x-6= 10

x= 10+6

x= 16