Б
f(x)=(a-x)/x
f(f(x))=(a-(a-x)/x):(a-x)/x=(ax-a++x)/x:(a-x)/x=(ax-a+x)/x * x/(a-x)=
=(ax-a+x)/(a-x)
в
f(x)=(2x-1)/(3-5x)
f(1/x)=(2/x-1):(3/x-5)=(2-x)/x:(3x-5)/x=(2-x)/x * x/(3x-5)=(2-x)/(3x-5)
f(f(1/x))=(2-(2-x)/(3x-5)):[3(2-x)/(3x-5) -5]=
=(6x-10-2+x)/(3x-5) :(6-3x-15x+25)/(3x-5)=(7x-12)/(3x-5)*(31-18x)=
=(7x-12)/(3x-5) *(3x-5)/(31-18x)=(7x-12)/(31-18x)