Baked 3 Packet Pot Roast

1 (3-4 pound) chuck roast
1 packet ranch dressing mix
1 packet Italian dressing mix
1 packet brown gravy mix
1 cup water or beef broth
2 tablespoons olive oil
4-5 large carrots, peeled and cut into chunks
5-6 medium potatoes, peeled and quartered
1 large onion, quartered