x²+2xy-y²+3x-4y+9=0 (1)
x²+4xy-2y²-5x-8y+8=0 (2)
(1)×2-(2)可得x²+11x+10=0即(x+1)(x+10)=0
解得x=-1或者-10
当x=-1时y=1或-7
当x=-10时y=-12±√223(√223为根号下223)
解为x=-1,y=1；x=-1,y=-7；x=-10,-12+√223；x=-10,-12-√223