[-5/(a²-16)]x[(a+4)²/(a+2)]+a/(a²-4):3/(a-2)=
[-5/(a-4)(a+4)]·[(a+4)²/(a+2)]+[a/(a+2)(a-2)]·(a-2)/3=
[-5/(a-4)]·[(a+4)/(a+2)]+3a/(a+2)=
[(-5a-20)/(a+4)(a-2)]+3a/a+2)=
[-5a-20+3a(a+4)]/(a+4)(a+2)=
(-5a-20+3a²+12a)/(a+4)(a+2)=
(3a²+7a-20)/(a+4)(a+2)=
conditia a≠{-4,-2}
3a²+7a-20=0
Δ=49+4x3x20=289
a1=(-7+66)/6=59/6
a2=(7+66)/6=73/6