You can check this using a view on the case object by putting the creation date and closed date as filters - could you please elaborate on the requirement as I suppose you won't need a formula - rather a simple view should work if you need just the records.
I believe you can use the following formula.
OR (
IF(((TODAY()-10) < DATEVALUE( ClosedDate )) , True, False),
IF(((TODAY()-10) < DATEVALUE( CreatedDate )) , True, False))
First one is to check for the records created in last 10 days where as second one is to check for the closed cases.
You can simply create a custom view which checks for the formula field equal to Y
Note : If this answers your question, please mark this as Answered. Thus others can benefit too.