问题 填空题 已知|x+y-5|+2x+y-4=0,则yx=______. 答案 ∵|x+y-5|+2x+y-4=0,∴x+y-5=0,2x+y-4=0,解得x=-1,y=6,∴xy=-1×6=-6,故答案为-6.