Giúp mình với ạ _

Đáp án+Giải thích các bước giải:

 `a)`

`\frac{3x}{6y}` `(đk:y\ne0)`

`=\frac{3.x}{3.2y}`

`=\frac{x}{2y}`

`a)`

`\frac{2x^{2}}{8x^{3}}` `(đk:x\ne0)`

`=\frac{2x^{2}}{2x^{2}.4x}`

`=\frac{1}{4x}`

`a)`

`\frac{5xy}{10y}` `(đk:y\ne0)`

`=\frac{5y.x}{5y.2}`

`=\frac{x}{2}`

`b)`

`\frac{x+2}{x^{2}-4}` `(đk:x\ne\pm2)`

`=\frac{x+2}{x^{2}-2^{2}}`

`=\frac{x+2}{(x-2).(x+2)}`

`=\frac{1}{x-2}`

`b)`

`\frac{x-3}{x^{2}-9}` `(đk:x\ne\pm3)`

`=\frac{x-3}{x^{2}-3^{2}}`

`=\frac{x-3}{(x-3).(x+3)}`

`=\frac{1}{x+3}`

`b)`

`\frac{x^{2}-1}{x+1}` `(đk:x\ne-1)`

`=\frac{x^{2}-1^{2}}{x+1}`

`=\frac{(x-1).(x+1)}{x+1}`

`=x-1`

`c)`

`\frac{2x+4}{x+2}` `(đk:x\ne-2)`

`=\frac{2.(x+2)}{x+2}`

`=2`

`c)`

`\frac{x^{2}-25}{3x+15}` `(đk:x\ne-5)`

`=\frac{x^{2}-5^{2}}{3.(x+5)}`

`=\frac{(x-5).(x+5)}{3.(x+5)}`

`=\frac{x-5}{3}`

`d)`

`\frac{3x^{2}-3y^{2}}{2x^{2}+4xy+2y^{2}}` `(đk:x\ne-y)`

`=\frac{3.(x^{2}-y^{2})}{2.(x^{2}+2xy+y^{2})}`

`=\frac{3.(x-y).(x+y)}{2.(x^{2}+2.x.y+y^{2})}`

`=\frac{3.(x-y).(x+y)}{2.(x+y)^{2}}`

`=\frac{3.(x-y)}{2.(x+y)}`

`d)`

`\frac{2x^{2}-8x+8}{x^{3}-8}` `(đk:x\ne2)`

`=\frac{2.(x^{2}-4x+4)}{x^{3}-2^{3}}`

`=\frac{2.(x^{2}-2.x.2+2^{2})}{(x-2).(x^{2}+x.2+2^{2})}`

`=\frac{2.(x-2)^{2}}{(x-2).(x^{2}+2x+4)}`

`=\frac{2.(x-2)}{x^{2}+2x+4}.`