giúp tớ với mọi người ơi

`a)A=(\sqrt{x}-4)/(x+8\sqrt{x}+16)-\sqrt{x}/(x-16)(x>=0,x\ne16)`

`=(\sqrt{x}-4)/(\sqrt{x}+4)^2-\sqrt{x}/((\sqrt{x}-4)(\sqrt{x}+4))`

`=(\sqrt{x}-4)^2/((\sqrt{x}-4)(\sqrt{x}+4)^2)-(\sqrt{x}(\sqrt{x}+4))/((\sqrt{x}-4)(\sqrt{x}+4)^2)`

`=((\sqrt{x}-4)^2-\sqrt{x}(\sqrt{x}+4))/((\sqrt{x}-4)(\sqrt{x}+4)^2)`

`=(x-8\sqrt{x}+16-x-4\sqrt{x})/((\sqrt{x}-4)(\sqrt{x}+4)^2)`

`=(-12\sqrt{x}+16)/((\sqrt{x}-4)(\sqrt{x}+4)^2)`

`b)B=\sqrt{x}/(x-10\sqrt{x}+25)-1/(x-25)(x>=0,x\ne25)`

`=\sqrt{x}/(\sqrt{x}-5)^2-1/((\sqrt{x}-5)(\sqrt{x}+5))`

`=(\sqrt{x}(\sqrt{x}+5))/((\sqrt{x}-5)^2(\sqrt{x}+5))-(\sqrt{x}-5)/((\sqrt{x}-5)^2(\sqrt{x}+5))`

`=(\sqrt{x}(\sqrt{x}+5)-(\sqrt{x}-5))/((\sqrt{x}-5)^2(\sqrt{x}+5))`

`=(x+5\sqrt{x}-\sqrt{x}+5)/((\sqrt{x}-5)^2(\sqrt{x}+5))`

`=(x+4\sqrt{x}+5)/((\sqrt{x}-5)^2(\sqrt{x}+5))`

`C=(\sqrt{x}+3)/(x-6\sqrt{x}+9)-\sqrt{x}/(x-9)(x>=0,x\ne9)`

`=(\sqrt{x}+3)/(\sqrt{x}-3)^2-\sqrt{x}/((\sqrt{x}+3)(\sqrt{x}-3))`

`=(\sqrt{x}+3)^2/((\sqrt{x}+3)(\sqrt{x}-3)^2)-(\sqrt{x}(\sqrt{x}-3))/((\sqrt{x}+3)(\sqrt{x}-3)^2)`

`=(x+6\sqrt{x}+9-x+3\sqrt{x})/((\sqrt{x}+3)(\sqrt{x}-3)^2)`

`=(9\sqrt{x}+9)/((\sqrt{x}+3)(\sqrt{x}-3)^2)`