How do you find the vertical, horizontal or slant asymptotes for f(x) = (x+1) / (x+2)?

1 Answer
Feb 20, 2017

Vertical : uarr x=-2 darr.Horizontal : larr y=1 rarr. See this asymptotes-inclusive rectangular hyperbola in the Socratic graph.

Explanation:

y = f(x)=1-1/(x+2), in the form y = Q +R/S, where R is a polynomial of

degree lesser than that of S.

y = Q gives a /horizontal/slant/curvilinear asymptote and

{x = a zero of S} gives vertical asymptotes.

Here, y = Q = 1 gives the horizontal asymptote and

S = x+2 = 0 gives the vertical asymptote.

Interestingly,

(y-1)(x+2)=-1 is of the form

L_1L_2=constant, where L_1 and L_2 are linear.

So, this represents a hyperbola with asymptotes

L_1L_2=(y-1)(x+2)=0. The asymptotes are at right angles,

and so, the hyperbola is rectangular.

See this with asymptotes, in the Socratic graph.

graph{((y-1)(x+2)+1)(y-1+.001x)(x+2+.001y)=0x^2 [-10, 10, -5, 5]}