原方程等價(jià)于條件組：（*)x＞(a-1)/4.(**)4x²+4(a-1)x+a-1=0.⊿=16(a-1)(a-2).（一）當(dāng)⊿＝0時(shí),有a=1,或a=2.代入條件組中可知,a=1時(shí),有x＞0,且x=0.矛盾.當(dāng)a=2時(shí).有x＞1/4,且x=-1/2.矛盾.故⊿≠0.（二）當(dāng)⊿＞0時(shí),有a＜1或a＞2.此時(shí)方程4x²+4(a-1)x+a-1=0有兩不等實(shí)根x1,x2(x11/5≤a≤1.由前可知,a≠1.當(dāng)a=1/5時(shí),條件組中的方程為4x²-(16x/5)-(4/5)=0.===>x1=-1/5,x2=1.此時(shí),（a-1)/4=-1/5.滿足x1≤(a-1)/4,x2＞(a-1)/4.綜上可知,1/5≤a＜1.即a∈[1/5,1).