14.已知函数f(x)=2x−2f(x)=\sqrt{{2^x}-2}f(x)=2x−2.(1)求函数f(x)f(x)f(x)的定义域;(2)若fff(a)=1=1=1,求实数aaa的值;(3)若g(x)=f(log2∣x∣)g(x)=f(\log _{2}\vert x\vert )g(x)=f(log2∣x∣),求证:g(x)g(x)g(x)为偶函数,并求g(x)>2g(x)>2g(x)>2的解集.