Đáp án+Giải thích các bước giải:
`a,frac{\sqrt{75a^3}}{\sqrt{3a^5}}(a>0)`
`=\sqrt{frac{75a^3}{3a^5}}`
`=\sqrt{frac{25}{a^2}}`
`=frac{5}{a}(a>0)`
`b,P=frac{1}{x-y}.\sqrt{x^4.(x-y)^2}(x>0)`
`=frac{1}{x-y}.x^2.|x-y|`
Nếu `x>y->|x-y|=x-y`
`->P=frac{1}{x-y}.x^2.(x-y)`
`=x^2`
Nếu `x<y->|x-y|=-(x-y)`
`->P=-frac{1}{x-y}.x^2.(x-y)`
`=-x^2`