4 номер ....….............
=(y+6)/(4*(y+2))-(y+2)/(4*(y-2))+5/((y+2)(y-2))=
=((y+6)(y-2)-(y+2)(y+2)+5*4)/(4*(y+2)(y-2))=
(y²+4y-12-y²-4y-4+20)/(4*(x+2)(x-2))=4/(4*(x²-4))=1/(x²-4).