得三个等式x-2y=k2x+3y=k+1 x+y=1 将k=x-2y带入2x+3y=k+1得2x+3y=x-2y+1则x=-5y+1将x=1-y代入x=-5y+1则1-y=-5y+14y=0y=0所以x=1k=1-2x0=1
