[tex]A(x)=(\frac{2}{x-2}-\frac{2}{x+1}):\frac{2}{x(x+1)(x-2)}\\
a)x-2=0 \Rightarrow x=2\\
x+1=0 \Rightarrow x=-1\\
x=0\\
2-1+0=1\\
b)A(x)=\frac{2(x+1)-2(x-2)}{(x+1)(x-2)}\cdot\frac{x(x+1)(x-2)}{2}\\
A(x)=(2x+2-2x+4) \cdot \frac{x}{2}\\
A(x)=6 \cdot \frac{x}{2}\\
A(x)=3x\\
x^2+2A(x)+9=x^2+6x+9=(x+3)^2\\
c)Daca\ x=0\ \Rightarrow 0\cdot (2-\sqrt5)= 0\in Q\\
Dar x \neq 0 \Rightarrow x\notin R(deci\ nu\ exista)[/tex]
