The document discusses performing a limit calculation by replacing infinity with a variable R and taking the limit as R approaches negative or positive infinity. Several comments provide clarification on performing the calculation and taking the limit in both directions.

1. On a clean sheet of E­2 paper, please do
the following.
Jan 6­11:06 AM
Replace ­∞ with R, then take a limit as R approaches negative infinity
Jan 6­10:43 AM
1

2. Replace ∞ with R, then take a limit as R approaches infinity
Jan 6­10:58 AM
Jan 6­11:00 AM
2

3. Jan 6­11:01 AM
Jan 6­11:59 AM
3