m^2+2n^2+m+4/3n+17/36=0
(m^2+m+1/4)+2(n^2+2/3n+1/9)=0
(m+1/2)^2+2(n+1/3)^2=0
所以m+1/2=0,n+1/3=0
m=-1/2,n=-1/3