bài 2: rút gọn
a) \(\dfrac{3+\sqrt{3}}{\sqrt{3}}+\dfrac{\sqrt{6}-\sqrt{3}}{1-\sqrt{2}}\)
b) \(\sqrt{\dfrac{x-2\sqrt{x}+1}{x+2\sqrt{x}+1}}\) (x\(\ge\) 0
c) \(\dfrac{x-y}{\sqrt{y}-1}\sqrt{\dfrac{\left(y-2\sqrt{x}+1\right)^2}{\left(x-1\right)^4}}\) x \(\ne\) 1; y \(\ne\)1 ; y \(\ge\)0