22.對(duì)于函數(shù)f(x),若存在x∈R,使f(x
0)=x
0成立,則稱(chēng)x
0為f(x)的不動(dòng)點(diǎn).已知函數(shù)f(x)=ax
2+(b+1)x+(b-1)(a≠0).
(1)當(dāng)a=1,b=3時(shí),求函數(shù)f(x)的不動(dòng)點(diǎn);
(2)若對(duì)任意實(shí)數(shù)b,函數(shù)f(x)恒有兩個(gè)相異的不動(dòng)點(diǎn),求a的取值范圍;
(3)在(2)的條件下,若f(x)的兩個(gè)不動(dòng)點(diǎn)為x
1,x
2,且
,求實(shí)數(shù)b的取值范圍.