we haven't eaten seafood for a long time=>we last ate seafood was a long time ago.

`(3^9. 3^20. 2^8)/(3^24. 243. 2^6)`

`=(3^29. 2^8)/(3^24. 3^5. 2^6)`

`=(3^29. 2^8)/(3^29. 2^6)`

`=2^2=4`

`n-5 vdots n`

`=>5 vdots n` vì `n vdots n`

`=>n in Ư(5)={1,-1,5,-5}`

Vậy `n in {1,-1,5,-5}` thì `n-5 vdots n`

`3|x-2|=15=>|x-2|=5=>x-2=5\or\x-2=-5=>x=7\or\x=-3`

`\text{A,An ninh quốc phòng,phát triển kinh tế}`

`\text{C.Trường Sa}`

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

`<=>x^2=(3x^2-6x-3)(x^2+4x+4)`

`<=>x^2=3x^4+6x^3-15x^2-36x-12=0`

`<=>3x^4+6x^3-16x^2-36x-12=0`

`<=>x=2,44\or\x=-0,42\or\x=-1,577\or\x=-2,449`

`x^2=3`

`=>x=\sqrt{3}\or\x=-\sqrt{3}`

`x^2=36`

`<=>x^2=(+-6)^2`

`<=>x=+-6`

`x^2=25`

`<=>x^2=(+-5)^2`

`<=>x=+-5`

`2x^2+(-20)=55`

`<=>2x^2-20=55`

`<=>2x^2=75`

`<=>x^2=75/2`

`<=>x=+-\sqrt{75/2}`

`2(x-1)^2+5^0=9`

`<=>2(x-1)^2+1=9`

`<=>2(x-1)^2=8`

`<=>(x-1)^2=4`

`<=>x-1=2\or\x-1=-2`

`<=>x=3\or\x=-1`

Vâng ạ ^^

Tưởng lỗi chứ nhở =))?