Square root

(?(4+2?(3)) +?(11-8*?(4-2?(3)) ))

http://en.wikipedia.org/w/index.php?title=Nested_radical&oldid=511727386#Denesting_nested_radicals

(?(4+2?(3)) +?(11-8*?(4-2?(3)) ))

=1 + ?(3) + ?(11-8*(?(3)-1) )

=1 + ?(3) + ?(19-8*(?(3)) )

=1 + ?(3) + 4-?(3)

=5