3/a>=15/21/a-5/2>=0(2-5a)/2a>=0a(5a-2)<=0 and a≠00 3/a<=31/a-1<=0(1-a)/a<=0a(a-1)>=0 and a≠0a<0 or a>=1故a<0 or 0=1 分式不等式基本方法：P/Q>=0化为PQ>=0(Q≠0)P/Q<=0化为PQ<=0(Q≠0)
