1/3x+2y=k x+6y=3k①4/3x+4y=k-4 4x+12y=3k-12x+3y=3k/4-3②x+y=-7/2③①-③5y=3k+7/2②-③2y=3k/4-3+7/2所以y=(3k+7/2)/5=(3k/4+1/2)/26k+7=15k/4+5/29k/4=-9/2k=-2y=(3k+7/2)/5=-1/2x=-7/2-x=-3