Make sure above all things if you truly wish to improve, is pay attention solely to yourself. You will be bogged down if you think that players feeding is truly what affects what happens game to game.
Firstly, I don't believe that anybody at any elo will magically be able to carry (if it's a fair match. ie no smurfing) when there are 5 people on the other team more or less the same skill level as you, but now one/two of them are fed.
Secondly, this is where my advice comes in, which is not by any means easy to take in and use: Always blame yourself, there is nobody you can control in ranked and who can pull through to be that effective person in the long run more than you. There will be many games that you will lose and I strongly believe that the best skill you can have in ranked is patience.
Combining the aforementioned things will not allow you to carry a single game after a player feeds horribly, but what it will do is give you an appreciation for learning even when losing. This learnt skill will allow you to be the best Silver V in your following games and in doing so will push you up in the ranks. Be the best at your elo and you will be promoted. Ask yourself, "What could I have done better?" and there is always an answer somewhere.
Just realized I ranted way too long because that advice is something I wish somebody could I told me when I was Bronze/Silver. Sorry in advance.
If you want a really straight forward and dumbed-down answer for winning a single game with a feeder(s), it can be broken done into a few broad steps:
- Win your lane. Push towers and relieve pressure from the rest of the map so the feeder(s) can farm and rejoin the game.
- Mute toxic people and only use chat for solid advice. Say no to surrenders.
- In your case, as a carry (I'm just going to assume marksman since mid can be covered fully with 1. and 2.), you should freeze bot lane and tell your support to roam. Having a large creep score will put you at an incredibly high advantage when it comes to compromising for your teammates.
- Above all else: Do not die. If you die while teammates are feeding then it's a lost cause. Make sure you make it a big deal for yourself when you die so it really gets nailed into your head.
Fun little Sp4zie video that illustrates my points with gameplay, commentary and music niceness.
Verbal Diarrhea finally stopped.
Hopefully this helped you in some way.
Best of luck on the Rift,
Afro