Show that fx57x1 and f1x7x75 are inverses Choose the appropr

Show that f(x)=5/7^x+1 and f^-1(x)=7x-7/5 are inverses Choose the appropriate equality that will show that f(x) and f^-1(x) are inverses (f.f^-1)(x)= (f^-1.f)(x)=1 (f.f^-1)(x)= (f^-1.f)(x)=x (f.f^-1)(x)= (f^-1.f)(x)=1 (f.f^-1)(x)= (f^-1.f)(x)=x

Solution

Replace x by f^-1(x) in f(x)
=> 5/7(7x-7)/5+1
=> (7x - 7)/7 + 1 = >   x - 1 + 1 => x
=> f(f^-1(x)) = x