I'm pretty new to piano (but not to instruments) and everything i learnt before was from watching videos or listening to someones play, rarely tabs. But now i decided to learn reading some scores and chords and other basic music theory.
I decided to learn Bach's prelude BWV 846, so i took the score http://www.sheetmusic2print.com/Media/Bach/Prelude-1-BWV-846.gif and someone's performance (learning starts at 1:18)
So he gives chords one by one : C, Dm7, ...
What I have learnt before is that Dm7 is 1,3b,5,7b but he plays C in the base, so it would be third inversion of Dm7. Is there no difference in saying: "now we play normal Dm7, and now we play it's third inversion"? I'm confused why he didn't write Dm7/C.
Do we only use slashes (like C/G#) when the base note is out of the chord (in C it is C E G)?
I'd really love to hear some explanation about this, because i'm confused about it for some long time. Cheers!