Learning-Hindi.com has great Hindi articles. I used to use it when I took Hindi courses at my University. http://www.learning-hindi.com/post/1116750602/lesson-48-nouns-in-the-oblique-case
Wow, it's lesson no. 48 there! Dunno if it's strategically so clever for Duolingo to be teaching it so early on. Any advice from more advanced users: Should I bother getting to grips with the oblique case now, or should I continue on the tree and focus on learning more vocab first?
I've read all the comments thus far, but it doesn't look like there's a definitive answer as to why it's उसके and not उसका. Is it definitely because जाना requires its object to be in the oblique despite not having a postposition? If so, may that please be added to the Oblique Case Lesson and Tips? Thank you!
Yes, this would be referring to someone else's home. If Raj were going to his own home, the sentence would read: राज अपने घर जाता है।
The word अपना doesn't really have a convenient translation in English. You could think of it as "his own"/"her own"/"their own"/"your own"/"my own"/etc.
मैं उसका खाना खाता हूँ।
I eat his/her food.
मैं अपना खाना खाता हूँ।
I eat my (own) food.
Just do see what would happen, I tried "Raj goes to its home." I was called wrong.
Admittedly, things don't generally have houses. But is that not a grammatically valid interpretation? What if I had been talking about a fraternity and I wanted to say "Raj goes to its (the fraternity's) house"?