TL

x+4/5=2/3                                                3x + 1/2=4/3

     x  =2/3-4/5                                          3x         =4/3+1/2

     x  =-2/15                                              3x       =11/6

                                                                   x       =11/6:3

                                                                   x      =11/18

nha bn

HT

Câu a:

2.(x + 2/5) + 1 1 /4 = 11/20

2x + 4/5 + 5/4 = 11/20

2x = 11/20 - 5/4 - 4/5

2x = 11/20 - 25/20 - 16/20

2x = -30/20

2x = -3/2

x = -3/2 : 2

x = - 3/4

Vậy x = - 3/4

Câu b:

x - 1 1/8 - 2/3x - 5/6x = 75%

(x - 2/3x - 5/6x) = 75% + 1 1/8

x (1 - 2/3 - 5/6) = 3/4 + 9/8

x (6/6 - 4/6 - 5/6) = 6/8 + 9/8

x.(-1/2) = 15/8

x = 15/8 : (-1/2)

x = 15/8 x (-2)

= -15/4

a) \(2.\left(x+\frac{2}{5}\right)+1\frac{1}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)+\frac{5}{4}=\frac{11}{20}\)

\(2.\left(x+\frac{2}{5}\right)=\frac{-7}{10}\)

\(x+\frac{2}{5}=\frac{-7}{20}\)

\(x=\frac{-13}{20}\)

Vậy \(x=\frac{-13}{20}\)

b)\(x-1\frac{1}{8}-\frac{2}{3}x-\frac{5}{6}x=75\%\)

  \(\left(x-\frac{2}{3}x-\frac{5}{6}x\right)-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x-\frac{9}{8}=\frac{3}{4}\)

\(\frac{-1}{2}x=\frac{15}{8}\)

\(x=\frac{-15}{4}\)

Vậy \(x=\frac{-15}{4}\)

Câu a:

xem lại đề bài

Câu b:

5 2/8x - 1/9 = 4 3/5

42/8x - 1/9 = 23/5

21/4x = 23/5 + 1/9

21/4x = 207/45 + 5/45

21/4x = 212/45

x = 212/45: 21/4

x = 212/45 x 4/21

x = 848/945

Vậy: x = 848/945

Câu c:

45%x - 2/3x = 75%

9/20x - 2/3x = 3/4

x(9/20 - 2/3) = 3/4

x(27/60 - 40/60) = 3/4

x.(-13/60) = 3/4

x = 3/4 : (-13/60)

x = 3/4 x (-60/13)

x = - 45/13

Vậy x = - 45/13

a,Ta có : 3x+23=(x+4).3+11

x+4=x+4

Vì (x+4).3 chia hết cho x+4

=> 11 chia hết cho x+4

Vì x+4 là ước của 11

=> x = 7

câu b làm sao bạn ơi

Câu a:

x - 1: 4/3 + 9/16 = - 5^2/4^2

x - 1 x 3/4 + 9/16 = - 25/16

x - 3/4 + 9/16 = - 25/16

x - 3/4 = -25/16 - 9/16

x - 3/4 = -17/8

x = - 17/8 + 3/4

x = -11/8

Vậy x = -11/8

Câu b:

5/2x + 2 - 3 1/2 = 1/6

5/2x + 2 - 7/2 = 1/6

5/2x = 1/6 + 7/2 - 2

5/2x = 1/6 + 21/6 - 12/6

5/2x = 5/3

x = 5/3 : 5/2

x = 2/3

a) \(\dfrac{1}{2}-\left(x+\dfrac{1}{3}\right)=\dfrac{5}{6}\)

\(\Rightarrow x+\dfrac{1}{3}=\dfrac{1}{2}-\dfrac{5}{6}\)

\(\Rightarrow x+\dfrac{1}{3}=\dfrac{-1}{3}\)

\(\Rightarrow x=\dfrac{-1}{3}-\dfrac{1}{3}\)

\(\Rightarrow x=\dfrac{-2}{3}\)

b)\(\dfrac{3}{4}-\left(x+\dfrac{1}{2}\right)=\dfrac{4}{5}\)

\(\Rightarrow x+\dfrac{1}{2}=\dfrac{3}{4}-\dfrac{4}{5}\)

\(\Rightarrow x+\dfrac{1}{2}=\dfrac{-1}{20}\)

\(\Rightarrow x=\dfrac{-1}{20}-\dfrac{1}{2}\)

\(\Rightarrow x=\dfrac{-11}{20}\)

c) \(\dfrac{3}{35}-\left(\dfrac{3}{5}+x\right)=\dfrac{2}{7}\)

\(\Rightarrow\dfrac{3}{5}+x=\dfrac{3}{35}-\dfrac{2}{7}\)

\(\Rightarrow\dfrac{3}{5}+x=\dfrac{-1}{5}\)

\(\Rightarrow x=\dfrac{-1}{5}-\dfrac{3}{5}\)

\(\Rightarrow x=\dfrac{-4}{5}\)

d)\(\dfrac{2}{3}.x=\dfrac{4}{27}\)

\(\Rightarrow x=\dfrac{4}{27}:\dfrac{2}{3}\)

\(\Rightarrow x=\dfrac{2}{9}\)

e) \(\dfrac{-3}{5}.x=\dfrac{21}{10}\)

\(\Rightarrow x=\dfrac{21}{10}:\dfrac{-3}{5}\)

\(\Rightarrow x=\dfrac{-7}{2}\)

giúp mình với các bạn!

câu a+b dùng quy tắc chuyển vế

c, 3.(1/2-x)-5.(x-1/10)=-7/4

=>(3.1/2-3x)-(5x-5.1/10)=-7/4

=>3/2-3x-5x+1/2=-7/4

=>(3/2+1/2)-(3x+5x)=-7/4

=> 2-8x=-7/4

=>8x=15/4

=>x=15/4:8

=>x=15/32

a) 2.(1/4 - 3x) = 1/5 - 4x
=> 1/2 - 6x = 1/5 -4x
=> -6x + 4x = 1/5 - 1/2
=> -2x         = -3/10 = 3/20
b) 4.(1/3 - x) + 1/2 = 5/6 +x 
=> 4/3 - 4x + 1/2 = 5/6 +x
=> -4x - x = 5/6 - 4/3 - 1/2
=> -5x = -1
=> x= 1/5
c) 3. (1/2 - x) -5. ( x - 1/10) = -7/4
=> 3/2 - 3x - 5x + 1/2 = -7/4
=> -3x - 5x = -7/4 - 3/2 - 1/2 
=> -8x = -15/4
=> x = 15/32