x²-2x/x²-4÷2x/x+2+(x+2);
=[x(x-2)/(x-2)(x+2)]÷2x/(x+2)+(x+2)
=[ x/x+2](x+2)/2x+(x+2)
=1/2+x+2
=x+3/2
(1/a+2-1)÷a²-1/a+2
=(1-a-2)/(a+2)÷a²-1/a+2
=(-1-a) /(a+2)÷ (a+1)(a-1)/(a+2)
=-1/( a-1)
=1/(1-a)