# Thread: limit at infinity of a difference of squares

1. ## limit at infinity of a difference of squares

How does one tackle a question like

limit as x -> + or - inf of [sqrt(f(x)) - sqrt(g(x))]

f(x) and g(x) are both quadratics of the form ax^2 + bx + c

I multiplied by the conjugate but then I get square roots in the denominator going to infinity.

here is the question:

after multiplying by the conjugate I get

Then i divide both top and bottom by x to get 11/4

if I take the limit going to negative infinity will the answer still be 11/4?

2. ## Re: limit at infinity of a difference of squares

Yes it will be.