@ sonia
Hi...we know that the the pic that optimum will be where the indiff curve is tangent to the budget curve..
Slope of indiff curve =2y/x ....slope of budget curve is 2x/2y
Equatiing we get, x= root over 2*y
now this must satisfy the equation of the circcle ..putiting it in X^2 +y^2=12, we get y=2 and X=rootover 8..ths satisfies the constraint that X<3 and Y<3..so no problem
I hope this helps