Question

Mọi người ơi giúp mình với 

Answer 1

`a)x=64`

`=>N=sqrtx/(sqrtx-3)=8/(8-3)=8/5`

`b)M=(2sqrtx)/(sqrtx-3)-(x+9sqrtx)/(x-9)`

`=(2x+6sqrtx-x-9sqrtx)/(x-9)`

`=(x-3sqrtx)/(x-9)`

`=sqrtx/(sqrtx+3)`

`P=M.N=x/(x-9)`

`c)` So sánh gì với 1?

Answer 2

a) Thay x=64(TMĐK) vào N ta có: 

\(N=\dfrac{\sqrt{64}}{\sqrt{64}-5}=\dfrac{8}{3}\)

Vậy x=64 thì N=\(\dfrac{8}{3}\)

b) \(P=M.N\)

\(P=\dfrac{2\sqrt{x}}{\sqrt{x}-3}-\dfrac{x-9\sqrt{x}}{x-9}.\left(\dfrac{\sqrt{x}}{\sqrt{x}-5}\right)\)

\(P=\dfrac{2\sqrt{x}}{\sqrt{x}-3}-\dfrac{x-9\sqrt{x}}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}.\left(\dfrac{\sqrt{x}}{\sqrt{x}-5}\right)\)

\(P=\dfrac{2\sqrt{x}\left(\sqrt{x}+3\right)-x+9\sqrt{x}}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}.\dfrac{\sqrt{x}}{\sqrt{x}+5}\)

\(P=\dfrac{x+15\sqrt{x}}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}.\dfrac{\sqrt{x}}{\sqrt{x}+5}\)

\(P=\dfrac{x}{\left(\sqrt{x}-3\right)\left(\sqrt{x} +3\right)}\)

\(P=\dfrac{x}{x-9}\)