y=-31/2x²+2x-1=-3两边乘2x²+4x+4=0(x+2)²=0x+2=0x=-2y=51/2x²+2x-1=5两边乘2x²+4x-12=0(x+6)(x-2)=0x=-6,x=2
Y=3.X=4Y=5,X=8