#(x^2-6x+8)/(x^2-x-2)#
Factor numerator and denominator:
#((x-4)(x-2))/((x+1)(x-2)#
We are able to cancel #(x-2)#, This shows that this is a removable discontinuity.
So there is a hole at #x=2#
#((x-4)cancel((x-2)))/((x+1)cancel((x-2)))=(x-4)/(x+1)#
Vertical asymptotes occur where the function is undefined.
#(x-4)/(x+1)#
is undefined for #x=-1# ( division by 0 )
So, the line #color(blue)(x=-1)# is a vertical asymptote.
Domain will therefore be:
#{x in RR : x != -1}#
#(x-4)/(x+1)#
Divide by #x#:
#(x/x-4/x)/(x/x+1/x)=(1-4/x)/(1+1/x)#
as #x->-oo# , #color(white)(888)(1-4/x)/(1+1/x)->(1-0)/(1+0)=1#
as #x->oo# , #color(white)(888888)(1-4/x)/(1+1/x)->(1-0)/(1+0)=1#
The line #color(blue)(y=1)# is a horizontal asymptote.
GRAPH: