A Jupyter notebook only displays the result of the last expression in any given cell. The other lines of code are executed, but their results are simply not displayed unless they call an explicit output function.
If you want to display both strings, you can (a) put then in separate Jupyter cells, or (b) manually call display (the multimedia analogue of println) on the things you want to show, e.g.
display(L"\sqrt{x}")
display(L"\frac{1}{x+1}")