Hello, I need some help with this:

Prove: lim x --> -1- 5/(x+1)^3 = neg. infinity

I am not sure how to do that.

a=-1

For a limit against neg. infinity I know that

if 0 < |x-a| < delta then f(x) < N

and for a left-hand limit I know

if a-delta < x < a then |f(x) - L| < epsilon

So I have

5/(x+1)^3 < N if |x+1| < delta

and

-1-delta < x < -1 if ???

I do not know how to combine them.

Thanks for any hints..