方程1化为：(x-3y)(x+y)=0则有x-3y=0, 或x+y=0当x-3y=0时,代入2式得：x-3/4*x^2=0, 解得：x=0, 4/3, 故有y=x/3=0, 4/9当x+y=0时,代入2式得：x+1/4x^2=0, 解得：x=0, -4, 故有y=-x=0, 4 因此共有3组不同(0,0), (4/3, ...