I have a site with 50 keywords but currently i m targeting only 3 keywords. How to promote rest of 47 keywords without make back links.

By the use of LSI(latent semantic indexing) which means use of these co-related keywords in article and blog content.

I am also looking for this question answer If some one have any specific answer please tell me

Whenever you build links for those three keywords, try to use those remaining keywords in link building techniques which you are using. And choose only those keywords which have enough demands otherwise to targeting those keywords which have poor demand, it is waste of time to promote them.

We can promote the keywords by targeting only those keywords which is very important.

Firstly the anchor text is very important in the keyword promotion. Then I suggest you to post links in the relative sites. Some one will say that amount is the king, but without quality backlinks your site will be punished by google.