How do you find the asymptotes for f(x)= (x^2+4x+3)/(x^2 - 9)?

2 Answers
Mar 7, 2016

vertical asymptote=-3,+3
horizontal asymptote = 1

Explanation:

The vertical asymptote is equal to denominator set to zero.Given that your denominator has a x squared the result will be x=+- 3. This is because (-3)^2=9and (3)^2=9 and when you subtract both with 9, both are equal zero.

The horizontal asymptote in this case is equal to the division of the x with largest exponent in both numerator and denominator .
x^2/x^2= 1

Mar 7, 2016

vertical asymptote x = 3
horizontal asymptote y = 1

Explanation:

First step is to factor the function:

(x^2+4x+3)/(x^2-9) =( (x+3)(x+1))/((x+3)(x-3))

and simplifying : (cancel(x+3)(x+1))/(cancel(x+3)(x-3))

left with (x+1)/(x-3)

Vertical asymptotes occur as the denominator of a rational function tends to zero. To find the equation let denominator equal zero.

solve: x - 3 = 0 → x = 3 is equation of asymptote.

Horizontal asymptotes occur as lim_(x→±∞) f(x) → 0

now (x+1)/(x-3) =( x/x + 1/x)/(x/x -3/x) = (1+1/x)/(1 -3/x)

as x approaches ∞ , 1/x " and " -3/x → 0

hence y = 1 is the asymptote

here is the graph of the function.
graph{(x^2+4x+3)/(x^2-9) [-10, 10, -5, 5]}