You are confused:
DB2 V7.1 = V7 base code or FP1-FP2
DB2 V7.2 = V7 FP3-FP14 (or whatever the latest is)
DB2 V8.1 = V8 base code or FP1-FP6
DB2 V8.2 = V8 FP7-FP10
If you are running DB2 on Windows, you can intall the latest fixpack of V8 (FP10) on top of V7. If you have Linux or UNIX, you must install 8.1 base code first, then upgrade to FP10.