f1(x)=x^2,f2=(x^-1),f3(x)=x^3,则f1(f2(f3(2007)))=?

问题描述:

f1(x)=x^2,f2=(x^-1),f3(x)=x^3,则f1(f2(f3(2007)))=?

2007^(-6)

f3(2007)=2007^3
f2(f3(2007)=f2(2007^3)=2007^6-1
f1(f2(f3(2007)))=f1(2007^6-1)=(2007^6-1)^2

f3(2007)=2007^3
f2(f3(2007))=f2(2007^3)=(2007^3)^(-1)=2007^(-3)
f1(f2(f3(2007)))=[2007^(-3)]^2=2007^(-6)