Bài 1 (2,5 điểm): Rút gọn biểu thức: a) A = $\sqrt{36}$.$\sqrt{64}$ + $\sqrt{225}$: $\sqrt{25}$ b) B= $\frac{x\sqrt{x}- \sqrt{x}}{x-1}$  (x$\geq$ 0; x$\neq$ 1)

`Accnswer`

`A=sqrt{36}.sqrt{64}+sqrt{225}:sqrt{25}`

`->A=sqrt{6^2}.sqrt{8^2}+sqrt{15^2}:sqrt{5^2}`

`->A=6.8+15:5`

`->A=48+3`

`->A=51`

`B=(x sqrt{x}-sqrt{x})/(x-1)(x>=0;x!=1)`

`->B=(sqrt{x}(x-1))/(x-1)`

`->B=sqrt{x}`