How do you find the vertical, horizontal and slant asymptotes of: f(x) =(x^2+6x-9)/(x-2)f(x)=x2+6x9x2?

1 Answer
Jul 3, 2016

V.A.: x=2, S.A.: y=x+8

Explanation:

The vertical asymptote depends on the domain of the function, then since it must be:

x!=2x2,

the vertical asymptote is the line x=2x=2

graph{(x^2+6x-9)/(x-2) [-10, 10, -5, 5]}

In fact

lim_(x rarr2)(x^2+6x-9)/(x-2)=7/0=oo

There are no horizontal asymptote, because

lim_(x rarroo)(x^2+6x-9)/(x-2)=oo

Maybe the function has a slant asymptote, so let's calculate

m=lim_(x rarroo)(x^2+6x-9)/(x-2)*1/x=1

and

n=lim_(x rarr2)(x^2+6x-9)/(x-2)-mx=

=lim_(x rarr2)(x^2+6x-9)/(x-2)-x=

=lim_(x rarr2)(cancelx^2+6x-9-cancelx^2+2x)/(x-2)=

=lim_(x rarr2)(8x-9)/(x-2)=8

So the equation of the slant asymptote is

y=x+8