No, it won't hold. My 42-incher tumbled down nicely onto the floor despite using strong expanders. My son was very surprised when he pulled out the arm and the whole thing crashed onto the parquet. I sawed a hole in the plasterboard halfway over the stud and inset a small OSB board behind it, also cross-braced between the studs. Then added new plasterboard, spackle, and paint. A bit more work than just attaching the board to the plasterboard, but neater...julbingo said:
If you're going to glue, use ESSTACK PRO1, and instead of a metal expander, use Plattiplugg. Both are in a class of their own. Plattiplugg holds as much as the board and cannot be pulled out like a metal expander. It costs a few kronor more but is entirely worth the 20-30:- it costs.