For all but one positive values of a, the function f(x, y ) = xtax .yty has exactly one critical point. What value of a is the exception? a = Check (3) Overview standard function logic vector abc unit epperton.. 9 Search ENG 9:57 P fuction W US 3/9/2023 FZ F3 F4 F5 F6 F7 F8 FO F10 F12 A /A Prt Sc Insert Delete # & Backspace W m R P