Hi .. Do you think buying an exact match domain name .com , and redirecting it (301) to a sub page in my website that I optimize for that keyword will help with SEO ? Thanks
Yes, this can add value to your actual website, but the redirecting domain should have a good content and should be fully optimized.
Without content Google will not show website on Google than how you get traffic from redirecting it (301).
If you will do 301 redirect then this domain will be washed off from Google's index after sometime and you gain nothing of using this technique.