`x<-3/4=>x+3/4<0`

`=>|x+3/4|=-x-3/4`

`=>A=-x-3/4-2`

`=>A=-x-11/4`

`sqrt{x^2-25}-6=3sqrt{x+5}-2sqrt{x-5}(x>=5)`

`<=>sqrt{(x-5)(x+5)}+2sqrt{x-5}=3sqrt{x+5}+6`

`<=>sqrt{x-5}(sqrt{x+5}+2)=3(sqrt{x+5}+2)`

`<=>(sqrt{x+5}+2)(sqrt{x-5}-3)=0`

Vì `sqrt{x+5}+2>0`

`<=>sqrt{x-5}-3=0`

`<=>sqrt{x-5}=3`

`<=>x-5=9<=>x=14(tm)`

Vậy `x=14`

`(3y+2x)(2x-3y)`

`=(2x)^2-(3y)^2`

`=4x^2-9y^2`

`(1/2x+3)(2x^2-4x+6)`

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

`=(x+6)(x^2-2x+3)`

`=x^3-2x^2+3x+6x^2-12x+18`

`=x^3+4x^2-9x+18`

`A=1+4+4^2+4^3+....+4^99+4^100`

`=>4A=4+4^2+4^3+4^4+...+4^100+4^101`

`=>4A-A=4^101-1`

`=>3A=4^101-1`

`=>A=(4^101-1)/3`

`sqrt{4x+20}-3sqrt{5+x}+4/3sqrt{9x+15}=6(x>=-5)`

`<=>sqrt{4(x+5)}-3sqrt{x+5}+4/3sqrt{9(x+5)}=6`

`<=>2sqrt{x+5}-3sqrt{x+5}+4sqrt{x+5}=6`

`<=>3sqrt{x+5}=6`

`<=>sqrt{x+5}=2`

`<=>x+5=4`

`<=>x=-1(tm)`

Vậy `x=-1`

`7//|x-2|-|1-2x|=0`

`<=>|x-2|=|1-2x|`

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

`<=>[(3x=3),(x=-1):}`

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

Vậy `x=1` hoặc `x=-1`

Bạn làm sai rồi (căn 2)a^2 chứ không phải là căn(2a^2)