x+y=-13-xy
(x+y)^2=x^2+y^2+2xy =29+2xy =169+26xy+(xy)^2
得xy=-10 x+y=-3
(x-y)^2=(x+y)^2-4xy=49
∴x-y=7或-7
∴x=-5 y=2 或x=-2 y=-5