(1)y=((x-1)/(x+1))²
√y=(x-1)/(x+1).逆求法
√y(x+1)=x-1
x(√y-1)=-√y-1
x=(-√y-1)/((√y-1)
故:f-1(x)=-(√x+1)/(√x-1) x≥0且x≠1
(2)把f-1(x)代入得:(1-√x)((-√x-1)/(√x-1))>a(a-√x)
√x+1>a(a-√x)
整理得:(a+1)√x-a²+1>0
(这时把它看成以√x为自变量的一条直线,在1/4和1/2处均大于0)
① 将x=1/4代入,整理得:2a²-a-3≦0 解得:-1<a<3/2
② 将x=1/2代入,整理得:2a²-√2a-(√2+1)≦0 解得:-√2/2<a<1+√2/2
取交集得:-√2/2<a<3/2
看不懂就再追问,