a)  \(\left(\frac{2x}{5}-1\right):\left(-5\right)=\frac{1}{7}\)

\(\frac{2x}{5}-1=\frac{1}{7}.\left(-5\right)\)

\(\frac{2x}{5}-1=\frac{-5}{7}\)

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

\(\frac{2x}{5}=\frac{2}{7}\)

\(=>2x.7=2.5\)

\(=>14x=10\)

\(=>x=\frac{5}{7}\)

c) \(\left|3,5+2,5x\right|-2,5=3,5\)

\(\left|3,5+2,5x\right|=3,5+2,5\)

\(\left|3,5+2,5x\right|=6\)

\(TH1\)  \(3,5+2,5x=6\)                                        \(TH2\)   \(3,5+2,5x=-6\)

            \(2,5x=6-3,5\)                                                            \(2,5x=-6-3,5\)

             \(2,5x=2,5\)                                                                    \(2,5x=-9.5\)

                    \(x=1\)                                                                    \(x=-3,8\)

     vậy \(x=1\) hoặc  \(x=-3,8\)

câu d) làm tương tự như câu c) 

ai trả lời nhanh thì đc k

a: =5,67x(2,5x0,4)=5,67

b: =1,47(36+64)=1,47x100=147

c: =(0,25x40)x0,68=0,68

d: =25,8(1,02-1,01)=25,8x0,01=0,258

e: =0,7x(0,25x4)=0,7

g: =5,6(4+3+2+1)=5,6x10=56

h: =(2,5x4)x(12,5x0,8)=10x10=100

m: =7,89(54-53-1)=0

cái này trong sách í

a) \(\frac{3x-2}{2}=\frac{1-2x}{3}\)

\(\Leftrightarrow3\left(3x-2\right)=2\left(1-2x\right)\)

\(\Leftrightarrow9x-6=2-4x\)

\(\Leftrightarrow13x-8=0\)

\(\Leftrightarrow x=\frac{8}{13}\)

b) \(\frac{x-1}{3}+2=3-\frac{2x+5}{4}\)

\(\Leftrightarrow\frac{4\left(x-1\right)+24}{12}=\frac{36-3\left(2x+5\right)}{12}\)

\(\Leftrightarrow4x-4+24=36-6x-15\)

\(\Leftrightarrow4x+20=-6x+21\)

\(\Leftrightarrow10x=1\)

\(\Leftrightarrow x=\frac{1}{10}\)

c) \(\frac{x-1}{5}+x=\frac{x+1}{7}\)

\(\Leftrightarrow\frac{7\left(x-1\right)+35x}{35}=\frac{5\left(x+1\right)}{7}\)

\(\Leftrightarrow7x-7+35x=5x+5\)

\(\Leftrightarrow37x=12\)

\(\Leftrightarrow x=\frac{12}{37}\)

d) \(2.\left(x-2.5\right)=0,25+\frac{4x-3}{8}\)

\(\Leftrightarrow8\left(x-2,5\right)=2+4x-3\)

\(\Leftrightarrow8x-20=4x-1\)

\(\Leftrightarrow4x=19\)

\(\Leftrightarrow x=\frac{4}{19}\)

a. = 0,25 : 0,25 + 0,4 x 2,5 + 0,2 x 5 

= 1 + 1 + 1

= 3

b. y x ( 7 + 1 + 12 - 6 - 4) = 45 

y x 9 = 45 

=> y = 5

a) \(2,5:4x=0,5:0,2\)

\(2,5:4x=\frac{5}{2}\)

\(4x=2,5:\frac{5}{2}\)

\(4x=1\)

\(x=\frac{1}{4}\)

Vậy \(x=\frac{1}{4}\)

b) \(\frac{1}{5}.x:3=\frac{2}{3}:0,25\)

\(\frac{1}{5}.x:3=\frac{8}{3}\)

\(\frac{1}{5}.x=\frac{8}{3}.3\)

\(\frac{1}{5}.x=8\)

\(x=8:\frac{1}{5}\)

\(x=40\)

Vậy \(x=40\)

a) \(\frac{2,5}{4x}=\frac{0,5}{0,2}\)

\(=>4x=\frac{0,2.2,5}{0,5}=1\)

\(=>x=\frac{1}{4}\)

b) \(\frac{1}{5}.\frac{x}{3}=\frac{2}{3}:0,25\)

\(=>\frac{x}{15}=\frac{4}{3}\)

\(=>x=\frac{4.15}{3}=20\)

2.a)\(\dfrac{3\text{x}-2}{2}\)=\(\dfrac{1-2\text{x}}{3}\)

<=>\(\dfrac{9\text{x}-6}{6}\)=\(\dfrac{2-4\text{x}}{6}\)

<=>9x-6=2-4x

<=>9x+4x=2+6

<=>13x=8

<=>x=\(\dfrac{8}{13}\)

1.a)2(x-0,5)+3=0,25(4x-1)

<=>2x-1+3=x-1phần4

<=>2x-x=-1/4+1-3

<=>x=-3/4