87 _(321_x ) ÷ 5 = 75

(321 _ x ) ÷ 5 = 87_75

(321 _ x ) ÷5 = 12

(321 _ x)        = 12 ×5

321 _ x        = 60

          X           = 321_60

         X            =  261

2)( 5x _2⁴) × 7³ = 2 × 7⁴

   ⁽5x _ 2⁴ )          = 2×7⁴÷7³

   ( 5x _ 16)          = 2×7

    5x _ 16             = 14

     5x                    = 14+ 16

      5x                   = 30

        X                   = 30÷5

         X                   = 6

3)93 + 3×(x_5)   = 3×5²

93+ 3× ( x _ 5)    = 75

3×( x _ 5)            = 75_93

3×(x _ 5 )             = _18

(X _ 5)                  = _18 ÷ 3

X _ 5                    = _6

X                          = _6 + 5

X                          = _1

Tớ chưa kịp làm tối về giải sau

a; \(\dfrac{93}{17}\): \(x\) + (- \(\dfrac{21}{17}\)) : \(x\) + \(\dfrac{22}{7}\): \(\dfrac{22}{3}\) = \(\dfrac{5}{14}\)

   \(\dfrac{94}{17}\) \(\times\) \(\dfrac{1}{x}\) - \(\dfrac{21}{17}\) \(\times\) \(\dfrac{1}{x}\) + \(\dfrac{3}{7}\) = \(\dfrac{5}{14}\)

    \(\dfrac{72}{17}\) \(\times\) \(\dfrac{1}{x}\) + \(\dfrac{3}{7}\) = \(\dfrac{5}{14}\)

     \(\dfrac{72}{17x}\)        = \(\dfrac{5}{14}\) - \(\dfrac{3}{7}\)

      \(\dfrac{72}{17x}\)      = - \(\dfrac{1}{14}\)

      17\(x\)       = 72.(-14)

       17\(x\)     = - 1008

         \(x\)       = - 1008 : 17

         \(x\)       = - \(\dfrac{1008}{17}\)

Vậy \(x\) \(=-\dfrac{1008}{17}\)

b; - \(\dfrac{32}{27}\) - (3\(x\) - \(\dfrac{7}{9}\))³ = - \(\dfrac{24}{27}\)

          - \(\dfrac{32}{27}\)  + \(\dfrac{24}{27}\) = (3\(x\) - \(\dfrac{7}{9}\))³ 

          (3\(x-\dfrac{7}{9}\))³ = - \(\dfrac{8}{27}\)

         (3\(x-\dfrac{7}{9}\))³ = (- \(\dfrac{2}{3}\))³

           3\(x-\dfrac{7}{9}\) = - \(\dfrac{2}{3}\)

           3\(x\)        = - \(\dfrac{2}{3}\) + \(\dfrac{7}{9}\)
           3\(x\)        = \(\dfrac{1}{9}\)

             \(x\)        = \(\dfrac{1}{9}\) : 3

             \(x\)       = \(\dfrac{1}{27}\)

Vậy \(x=\dfrac{1}{27}\)

Bài 1: 

a: \(\Leftrightarrow3^x\cdot10=810\)

\(\Leftrightarrow3^x=81\)

hay x=4

c: \(\Leftrightarrow5^x\cdot5+5^x\cdot\dfrac{1}{25}=126\)

\(\Leftrightarrow5^x\cdot\dfrac{126}{25}=126\)

\(\Leftrightarrow5^x=25\)

hay x=2

Bài 2: 

a: \(27^{11}=3^{33}\)

\(81^8=3^{32}\)

mà 33>32

nên \(27^{11}>81^8\)

c: \(625^5=\left(5^4\right)^5=5^{20}\)

\(125^7=\left(5^3\right)^7=5^{21}\)

mà 20<21

nên \(625^5< 125^7\)

a) 5^x=125

=> 5^x=5^2

=>x=2

b) 3^2*x=81

=>3^2*x=9^2

=>3^2*x=(3^2)^2

=>x=2

câu c chưa hiểu chỗ 5^2x3 hay 5^2*3 vậy ?

a) \(5^x=125\)

\(5^x=5^3\)

\(\Rightarrow x=3\)

b)\(3^{2x}=81\)

\(3^{2x}=3^4\)

\(\Rightarrow2x=4\)

\(x=4:2\)

\(x=2\)

c)\(5^{2x-3}-2.5^2=5^2.3\)

\(5^{2x-3}=5^2.3+5^2.2\)

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

\(5^{2x-3}=5^3\)

\(\Rightarrow2x-3=3\)

\(2x=3+3\)

\(2x=6\)

\(x=6:2\)

\(x=3\)

5^2x3 nha

`x/8=4/(-32)`

`(4x)/32=(-4)/32`

`4x=-4`

`x=-1`

Vậy `x=-1`.

`b)x-7/18=3 5/12`

`x-7/18=41/12`

`x=41/12+7/18`

`x=137/36`

Vậy `x=137/36`

`c)-3/8. 2/5+(-3)/8. 9/5-(-3)/8. 6/5`

`=-3/8. 2/5-3/8. 9/5+3/8. 6/5`

`=3/8(-2/5-9/5+6/5)`

`=3/8.(-1)`

`=-3/8`

a/|x|-2,5=27,5

=>|x|=27,5+2,5=30

=>x=30 hoặc x=-30

b/\(\dfrac{3}{4}+\dfrac{2}{5}.x=\dfrac{29}{60}\)

=>\(\dfrac{2}{5}.x\)=\(\dfrac{29}{60}-\dfrac{3}{4}\)=\(\dfrac{-4}{15}\)

=>x=\(\dfrac{-4}{15}:\dfrac{2}{5}\)=\(\dfrac{-2}{3}\)

c/(x-1)\(^5\)=-32

=>x-1=-2 vì (-2)\(^5\)=-32

=>x=-2+1=-1

d/\(\dfrac{4}{5}.x+0,5=4.5\)

=>\(\dfrac{4}{5}.x+0,5=20\)

=>\(\dfrac{4}{5}.x=20-0,5=19,5\)

=>\(x=19,5:\dfrac{4}{5}\)=\(\dfrac{195}{8}\)