Building links to subpage or also to homepage?


I would like to know your opinion on ranking a subpage. The domain itself is quite authoritative and the web ranks well for many keywords.

There is a sub-page that I need to rank and so far I optimized only that given subpage.

Do you think building anchors with that keyword would be good also to root domain? I never tried it because I though Google would not know which of those two is more suitable to be displayed for given keyword, but maybe you have another experience.