1.
Gọi $M\Big(x_0; \dfrac{2x_0}{x_0+1} \Big) \in (C)$
$\to$ PTTT : $y = \dfrac{2}{x_0+1}. (x-x_0) + \dfrac{2x_0}{x_0+1}$ $(d)$
$(d) \cap Ox$ tại $A \Big( - x_0^2;0\Big)$
$(d) \cap Oy$ tại $B \Big(0; \dfrac{2x_0^2}{(x_0+1)^2} \Big)$
$\Rightarrow \dfrac{1}{2}.x_0^2. \dfrac{2x_0^2}{(x_0+1)^2} = \dfrac{1}{4}$
$\to x_0= 1$ hoặc $x_0= \dfrac{-1}{2}$
$\to M\Big( 1;1\Big)$ hoặc $\Big(\dfrac{-1}{2};-2\Big)$
$\to D$
2. `C`
