1. x = 5/7

2. x = 125

cảm ơn

a,1.4/5.x =4/7

 4/5.x=4/7:1

4/5.x=4/7

x=4/7:4/5

x=5/7

mình chưa làm đc câu b nha

\(a.x=\frac{3}{4}-\frac{1}{2}=\frac{1}{4}\)

\(b.x=\frac{4}{7}:\frac{4}{5}=\frac{5}{7}\)

\(c.8x-7,8x=25\)

\(0,2x=25\Rightarrow x=125\)

\(=>x=25:\left(\dfrac{1}{2}-\dfrac{1}{5}\right)=25:\dfrac{3}{10}=\dfrac{250}{3}\)

\(\dfrac{x}{2}-\dfrac{x}{5}=25\)

\(\dfrac{5x}{10}-\dfrac{2x}{10}=25\)

\(\dfrac{5x-2x}{10}=25\)

\(\dfrac{3x}{10}=25\)

\(3x=10.25\)

\(3x=250:3\)

\(3x=\dfrac{250}{3}\)

thiếu dấu

\(\left(\frac{13}{4}-x.\frac{8}{5}\right).3=4\)

\(\left(\frac{13}{4}-x\cdot\frac{8}{5}\right)=4:3\)

\(\frac{13}{4}-x\cdot\frac{8}{5}=\frac{4}{3}\)

\(x\cdot\frac{8}{5}=\frac{13}{4}-\frac{4}{3}\)

\(x\cdot\frac{8}{5}=\frac{23}{12}\)

\(x=\frac{23}{12}:\frac{8}{5}\)

\(x=\frac{115}{96}\)

nhanh len mik h cho

2x - 138 = 2³ . 3²

=> 2x - 138 = 72

=> 2x = 72 + 138

=> 2x = 210

=> x = 105

10 + 2x = 4³ . 4²

10 + 2x =1024

2x = 1024 - 10

2x = 1014

x = 507

(3x - 2⁴) . 7³ = 2.7⁴

3x - 2⁴ = 2 . 7⁴ : 7³

3x - 16 = 14

3x = 14 + 16

3x = 30

x = 10

x⁴ = 16

=> x⁴ = 2⁴

=> x = 2

5^{x + 12} = 625

5^{x + 12} = 5⁴

=> x + 12 = 4

=> x = 4 - 12

=> x = -8

(x⁴)¹¹ = x

x⁴⁴ = x

=> x = 1; 0

1.
a) \(\frac{11}{2}-\frac{2}{3}:\left|2x+-\frac{3}{2}\right|=3\)
               \(-\frac{2}{3}:\left|2x+-\frac{3}{2}\right|=3-\frac{11}{2}\)
               \(-\frac{2}{3}:\left|2x+-\frac{3}{2}\right|=-\frac{5}{2}\)
                          \(\left|2x+-\frac{3}{2}\right|=-\frac{2}{3}:\left(-\frac{5}{2}\right)\)
                          \(\left|2x+-\frac{3}{2}\right|=\frac{4}{15}\)
\(\Rightarrow\left|2x+-\frac{3}{2}\right|\in\text{{}\frac{4}{15};-\frac{4}{15}\)}
Nếu, \(2x+\left(-\frac{3}{2}\right)=\frac{4}{15}\)
                               \(2x=\frac{53}{30}\)
                                  \(x=\frac{53}{60}\)
Nếu, \(2x+\left(-\frac{3}{2}\right)=-\frac{4}{15}\)
                               \(2x=\frac{37}{30}\)
                                  \(x=\frac{37}{60}\)
Vậy \(x\in\text{{}\frac{53}{60};\frac{37}{60}\)}
b) \(\left|\frac{2}{7}x-\frac{1}{5}\right|-\left|-x+\frac{4}{9}\right|=0\)
    \(\left|\frac{2}{7}x-\frac{1}{5}\right|=\left|-x+\frac{4}{9}\right|\)
\(\Rightarrow\left|\frac{2}{7}x-\frac{1}{5}\right|\in\text{{}-x+\frac{4}{9};-\left(x+\frac{4}{9}\right)\)}
Nếu, \(\frac{2}{7}x-\frac{1}{5}=-x+\frac{4}{9}\)
                          \(x=\frac{203}{405}\)
Nếu, \(\frac{2}{7}x-\frac{1}{5}=-\left(-x+\frac{4}{9}\right)\)
         \(\frac{2}{7}x-\frac{1}{5}=x-\frac{4}{9}\)
            \(\frac{2}{7}x-x=\frac{1}{5}-\frac{4}{9}\)
                 \(-\frac{5}{7}x=-\frac{11}{45}\)
                           \(x=\frac{77}{225}\)
Vậy \(x\in\text{{}\frac{203}{405};\frac{77}{225}\)}