How is "yang" functioning here? It is not qualifying "ini" in some way, is it? I was told it had to be "Try doing this one," instead of "Try doing this," but they both mean the same thing in my dialect of English.
How is "yang" functioning here?
It is not qualifying "ini" in some way, is it?
Yes, it is.
"yang' refers directlly to "ini", giving extra emphasis on "ini".
The same as in English, where the word "one" refers to "this" and gives it extra emphasis.
Coba kerjakan ini = Try doing this.
Coba kerjakan yang ini = Try doing this one.
In my dialect of English, "this one" does not express any extra emphasis. One does hear it more often when talking about the choice of one from a limited series.