∵ ax+ay+bx+by＞2ay+2bx∴ ax-ay-bx+by＞0∴ a(x-y)-b(x-y)＞0∴ (a-b)(x-y)＞0∴ a-b和x-y同号,设a-b=n,x-y=m,则转化为已知 mn＞0,证明：m/n+n/m≥2① m＞0 n＞0 则m/n+n/m≥2根号(m/n×n/m)=2② m＜0 n＜0 则m/n...