giup mik voi !!!!!!!!

`#Zi`

Đáp án:

Giải thích các bước giải:

 `a)` `1/9 . 27^x = 3^x`

`1/3^2 .` $\text{3}$$^{3x}$  `=3^x`

$\text{3}$$^{3x-2}$ `=3^x`

$\text{3}$$^{3x-2}$ `=x`

`3x=x+2`

`3x-x=2`

`2x=2`

`x=2:2`

`x=1`

~~~~~~~~~~~~~~~~~

`b)` `(3x+4)^2 - 8=41`

`9x^2 + 24x + 16-8=41`

`9x^2 + 24x+8=41`

`9x^2 + 24x+8-41=0`

`9x^2 + 24x - 33=0`

`3x^2 + 8x-11=0`

`3x^2 + 11x - 3x-11=0`

`x(3x+11)-3x-11=0`

`x(3x+11)-(3x+11)=0`

`(3x+11)(x-1)=0`

`3x+11=0` hoặc `x-1=0`

`x=-11/3` hoặc `x=1`

Vậy `x` $\in$ `{-11/3;1}`

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

`c)` `3(x+1/2)-x^3/3(x+1/2)=0`

`(x+1/2)(3 - x^3/3)=0`

`x+1/2 = 0` hoặc `3 - x^3/3 = 0`

`x=-1/2` hoặc `x =` $\sqrt[3]{9}$

Vậy `x=-1/2` hoặc `x=` $\sqrt[3]{9}$