10
1)(a+2)/(a-2)(a²+2a+4) -1/(a-2)(a+2)=(a²+4a+4-a²-2a-4)/(a-2)(a+2)(a²+2a+4)=
=2a/(a-2)(a+2)(a²+2a+4)
2)2a/(a-2)(a+2)(a²+2a+4) :(a+2)/a(2-a)(a²+2a+4)=
=2a/(a-2)(a+2)(a²+2a+4) *a(2-a)(a²+2a+4)(a+2)/(a+2)=-2a²/(a+2)²
3)-2a²/(a+2)² +1/a=(-2a³+a²+4a+4)/(a+2)²