(x﹣1)(x+1)=x2﹣1,
(x﹣1)(x2+x+1)=x3﹣1,
(x﹣1)(x3+x2+x+1)=x4﹣1,
……
关于x的不等式x2-2ax-8a2<0(a>0)的解集为(x1x2),且x2-x1=15,则a=( )
下列函数f(x)中,满足“对任意x1、x2∈(0,+∞),当x1<x2时,都有f(x1)>f(x2)”的是( )
—My keys. I can't remember ___________.