Ta có

`log_(1/4)x^2`

`=1/(log_(x^2) 1/4)`

`=1/(log_(x^2) 1-log_(x^2)4)`

`=1/(0-2log_(x^2)2)`

`=-1/2 log_2 x^2`

`=-1/2 . 2log_2 |x|`

`=-log_2 |x|`

`log_2 (x+3)-log_(1/4) x^2=1(x> -3)`

`<=>log_2 (x+3)-(-log_2 |x|)=1`

`<=>log_2 (x+3)+log_2 |x|=1`

`<=>log_2 (x+3)|x| =log_2 2`

`<=>(x+3)|x|=2`

Th1:

`x(x+3)=2`

`<=>x^2+3x-2=0`

`<=>[(x=-(3-sqrt17)/2 (tm)),(x=-(3+sqrt(17))/2(ktm)):}`

Th2:

`-x(x+3)=2`

`<=>x^2+3x+2=0`

`<=>[(x=-1(tm)),(x=-2(tm)):}`