Let x and y be real numbers such that xy=9 Find the set of all possible values of x+y
+2401 I think since sqrt(9) = +- 3, it can be all numbers other than -6 to 6 (non inclusive)
=^._.^=
+178 Use AM-GM for positive x,y, we can get that x+y>=6, and for negatives x+y<=-6.
So, it is either x+y>=6 or x+y<=-6.
