a,\(\frac{17}{12}\)

b,\(\frac{-134}{81}\)

c,x=2

d,x=7

\(\left(5^{2x}\cdot5^{x+2}\right):25=125^2\)   

\(5^{2x+x+2}=125^2\cdot25\)   

\(5^{3x+2}=\left(5^3\right)^2\cdot5^2\)   

\(5^{3x+2}=5^6\cdot5^2\)   

\(5^{3x+2}=5^8\)   

\(\Rightarrow3x+2=8\)   

\(3x=8-2\)   

\(3x=6\)   

\(x=6:3\)   

\(x=2\)

Tìm \(x\) câu a:

\(\frac13.x\) + \(\frac25.\left(x+1\right)\) = 0

\(\frac{5}{15}x\) + \(\frac{6}{15}x\) + \(\frac25\) = 0

\(\frac{11}{15}x\) = - \(\frac25\)

\(x=-\frac25:\frac{11}{15}\)

\(x\) = - \(\frac25\times\frac{15}{11}\)

\(x\) = - \(\frac{6}{11}\)

Vậy \(x=-\frac{6}{11}\)

Tìm \(x\) câu b:

\(x\) x 25% = 0,5

\(x\times0,25\) = 0,5

\(x=0,5:0,25\)

\(x=2\)

Vậy \(x=2\)

Câu 1a:

1/3x + 2/5(x + 1) = 0

1/3x + 2/5x + 2/5 = 0

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

x(1/3 + 2/5) = -2/5

x.(5/15 + 6/15) = -2/5

x.11/15 = - 2/5

x = - 2/5 : 11/15

x = - 6/11

Vậy x = -6/11

Câu b:

x . 25%. x = 0,5

x.x = 0,5 : 25%

x^2 = 2

x = - \(\sqrt2\); x = \(\sqrt2\)

Vậy x ∈ {- \(\sqrt2\); \(\sqrt2\) )

Câu 1a:

1/3x + 2/5(x + 1) = 0

1/3x + 2/5x + 2/5 = 0

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

x(1/3 + 2/5) = -2/5

x.(5/15 + 6/15) = -2/5

x.11/15 = - 2/5

x = - 2/5 : 11/15

x = - 6/11

Vậy x = -6/11

Câu b:

x . 25%. x = 0,5

x.x = 0,5 : 25%

x^2 = 2

x = - \(\sqrt2\); x = \(\sqrt2\)

Vậy x ∈ {- \(\sqrt2\); \(\sqrt2\) )

\(\Rightarrow\frac{2x}{4}-\frac{3}{5}=\frac{x}{4}\)

\(\Rightarrow\frac{2x}{4}-\frac{x}{4}=\frac{3}{5}\)

\(\Rightarrow\frac{x}{4}=\frac{3}{5}\)

=> 5x = 12

=> x= 12/5

bn luân sai r 

320 : ( x - 1 ) = ( 5³ - 5² ) : 4 + 15

<=> 320 : ( x - 1 ) = ( 125 - 25 ) : 4 + 15

<=> 320 : ( x - 1 ) = 100 : 4 + 15

<=> 320 : ( x - 1 ) = 40

<=> x - 1 = 8

<=> x = 9

240 : ( x - 5 ) = 2² . 5² - 20

<=> 240 : ( x - 5 ) = 4 . 25 - 20

<=> 240 : ( x - 5 ) = 80

<=> x - 5 = 3

<=> x = 8

70 : ( x - 3 ) = ( 3⁴ - 1 ) : 4 - 16

<=> 70 : ( x - 3 ) = 80 : 4 - 16

<=> 70 : ( x - 3 ) = 4

<=> x - 3 = 35/2

<=> x = 41/2

a) 320: (x-1) = (5³ - 5²):4 + 15         b) 240: (x-5) = 2².5² - 20      c) 70:(x-3) = (3⁴ - 1):4 - 16

    320: (x-1) = (125- 25): 4 + 15          240: (x-5) = 4.25 - 20            70:(x-3) = (81-1): 4 - 16

    320: (x-1) = 100:4 + 15                   240: (x-5) = 100 - 20              70: (x-3) = 80: 4 - 16

    320: (x-1) = 25 + 15                        240: (x-5) = 80                       70: (x-3) = 20  -16

    320: (x-1) = 40                                (x-5) = 240:80                        70: (x-3) = 4

    (x-1) = 320:40                                 (x-5) = 3                                 (x-3) = 70:4 

      (x-1) = 80                                      x = 5+3                                   (x-3) = 17,5

      x = 80+1                                        x = 8                                       x = 17,5 : 3

       x = 81                                                                                          x = 5,83 

a

\(5\frac{4}{7}:x+=13\)

\(\frac{39}{7}:x=13\)

\(x=\frac{39}{7}:13\)

\(x=\frac{3}{7}\)

\(\frac{4}{7}x=\frac{9}{8}-0,125\)

\(\frac{4}{7}x=1\)

\(x=1:\frac{4}{7}\)

\(x=\frac{7}{4}=1\frac{3}{4}\)