Đáp án:
$P=( √2-1).$$\dfrac{2+√2}{2√2}$ $=$ $\dfrac{(√2-1)(2+√2)}{2√2}$ $=$ $\dfrac{2√2+2-2-√2}{2√2}$
$= $$\dfrac{2√2-√2}{2√2}$ $= 0,5$
$Q=($$\dfrac{1}{√x-3}$+$\frac{1}{√x+3}$$)(1- $$\dfrac{3}{√x}$$) = [$$\dfrac{√x+3+√x-3}{(√x-3)(√x+3)}$$]($$\dfrac{√x-3}{√x}$ )
$=$ $\dfrac{2√x}{(√x-3)(√x+3)}$$ ($$\dfrac{√x-3}{√x}$ $) =$ $\dfrac{2}{√x+3}$ (Điều kiện $x>0; x$$\neq$$9$)
BẠN THAM KHẢO NHA!!!