How do you identify all asymptotes or holes for g(x)=(2x^2+3x-1)/(x+1)?

1 Answer
Dec 17, 2016

There is no hole. We have vertical asymptote at x=-1 and oblique asymptote at y=2x+1

Explanation:

Let us examine g(x)=(2x^2+3x-1)/(x+1).

As for the x=-1, although denominator x+1=0 but 2x^2+3x-1!=0, there is no common factor between numerator and denominator and hence we do not have any hole.

It is also apparent that as x->-1, (2x^2+3x-1)/(x+1)->oo

and as we have f(x)=(x^2+11x+18)/(2x+1), f(x)->oo or f(x)->-oo, as we approach x=-1 from negative or positive side.

Hence, we have a vertical asymptote at x=-1/2.

Further as 2x^2+3x-1=2x(x+1)+1(x+1)-2

As such, f(x)=(2x^2+3x-1)/(x+1)=2x+1-2/(x+1)

Hence, as x->oo. f(x)->2x+1

and we have an oblique asymptote at y=2x+1
graph{(2x^2+3x-1)/(x+1) [-10, 10, -5, 5]}