Prove Limit is Negative Infinity

Calculus
Section 1.7

Another limit prove question that you might never see on a test in a first-year calculus course bit interesting nonetheless. I need 43 done in step by step fashion.

 

first graph 5/(x+1)^3



as you can see, as x approaches -1 from the left,
and, as x approaches -1 from the right,

 

From the left, we get negative infinity.
From the right we get positive infinity.

So, the limit DNE. Yes?