由顶点,设y=a(x+1)^2+2
代入点(0,3/2),得3/2=a+2,得a=-1/2
故y=(-1/2)(x+1)^2+2
将(m,-m^2)代入函数得：-m^2=(-1/2)(m+1)^2+2
2m^2=(m+1)^2-4
m^2-2m+3=0
△=4-12=-8