\(\Leftrightarrow x^3-ax^2-4=\left(x^2+4x+4\right)\cdot a\left(x\right)=\left(x+2\right)^2\cdot a\left(x\right)\)

Thay \(x=-2\Leftrightarrow-8-4a-4=0\Leftrightarrow a=-3\)

\(\Leftrightarrow x^3+4x^2+4x+\left(-4-a\right)x^2-4⋮x^2+4x+4\)

\(\Leftrightarrow-4-a=4+x^2\)

\(\Leftrightarrow a=-4-4-x^2=-x^2-8\)

\(A=\left(8+2\cdot3-7\cdot\dfrac{13}{10}+3\cdot\dfrac{5}{4}\right):\left(\dfrac{5\sqrt{6}}{3}\right)^2\\ A=\left(14-\dfrac{91}{10}+\dfrac{15}{4}\right):\dfrac{50}{3}\\ A=\dfrac{173}{20}\cdot\dfrac{3}{50}=\dfrac{519}{1000}\)

Hình như đề bài của bạn bị lỗi rồi.

bạn ơi ghi lại đầu bài đi rồi mình làm chho nha

`a, x/7 =-4/14`

`=> 14x=7.(-4)`

`=>14x=-28`

`=>x=-28:14`

`=>x=-2`

`b,x/2=-2/-x`

`=>x/2=2/x`

`=>x.x=2.2`

`=>x^2=4`

`=>x= +-2`

`c,(x-1)/5=5/(x-1)`

`=>(x-1)^2 = 5.5`

`=>(x-1)^2=25`

`=>(x-1)^2=5^2`

\(\Rightarrow\left[{}\begin{matrix}x-1=5\\x-1=-5\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=6\\x=-4\end{matrix}\right.\)

`d,x+3/2=-12/16`

`=>x=-12/16 -3/2`

`=>x= -12/16 - 24/16`

`=>x= -36/16`

`=>x=-9/4`

* = nhân nhé

( ( x . 32 ) - 17 ) . 2 = 42

( ( x . 32 ) - 17 ) = 42 : 2

( ( x . 32 ) - 17 ) = 21

x . 32 = 21 + 17

x . 32 = 38

x = 38 : 32

x = 19/16

-15 ( x - 2 ) + 7 ( 3 - x ) = 7

-15x + 30 + 21 - 7x = 7

-15x - 7x = 7 - 21 - 30

-22x = -44

   x   = ( -44 ) : ( -22)

  x    = 2

Vậy x = 2

-12 ( x - 5 ) + 7 ( 3 - x ) = 5

-12x + 60 + 21 - 7x = 5

-12x - 7x = 5 - 21 - 60

-19x = -76

x      = ( -76 ) : (-19)

x      = 4

Vậy x = 4.

# HOK TỐT #

thanks

a) 5.3^x = 405

3^x = 81 = 3⁴

=> x = 4

b) 2^x : 8 = 4

2^x = 32 = 2⁵

=> x = 5

c) x⁶⁴ = x

=> x⁶⁴ - x = 0

x.(x⁶³ -1) = 0

=> x = 0

x⁶³ - 1 = 0 => x⁶³ = 1 => x = 1

KL: ...

phần d lm tương tự phần c nha bn

e) (x-2)⁵ = 243 = 3⁵

=> x - 2 = 3

x = 5

g) (x+1)³ = 125 = 5³

=> x + 1 = 5

 x = 4

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

  x-2+5=-x+3

     x+x=3+2-5

       2x=0

         x=0:2

         x=0

Vậy x=0

\(\dfrac{4}{5}\left(\dfrac{2}{3}x-\dfrac{9}{5}\right)-\dfrac{2}{5}\cdot\dfrac{-3}{7}=\dfrac{15}{4}\)

\(\Rightarrow\dfrac{2}{5}\left(\dfrac{2}{3}x-\dfrac{9}{5}\right)-\dfrac{-6}{35}=\dfrac{15}{4}\)

\(\Rightarrow\dfrac{2}{5}\left(\dfrac{2}{3}x-\dfrac{9}{5}\right)+\dfrac{6}{35}=\dfrac{15}{4}\)

\(\Rightarrow\dfrac{2}{5}\left(\dfrac{2}{3}x-\dfrac{9}{5}\right)=\dfrac{15}{4}-\dfrac{6}{35}=\dfrac{501}{140}\)

\(\Rightarrow\dfrac{2}{3}x-\dfrac{9}{5}=\dfrac{501}{140}:\dfrac{2}{5}=\dfrac{501\cdot5}{28\cdot5\cdot2}=\dfrac{501}{56}\)

\(\Rightarrow\dfrac{2}{3}x=\dfrac{501}{56}+\dfrac{9}{5}=\dfrac{2001}{280}\)

\(\Rightarrow x=\dfrac{2001}{280}:\dfrac{2}{3}=\dfrac{2001\cdot3}{280\cdot2}=\dfrac{6003}{560}\)