a)Show that the composition of two one-to-one functions f and g, is one-to-one.

b)Express (f o g)^-1 in terms of f^-1 and g^-1.

For a) I put down:

Assume f and g are one-to-one

g(x1) = x1

g(x2) = x2

f(x1) = x1

f(x2) = x2

g(x1)=g(x2) iff x1=x2

f(x1)=f(x1) iff x1=x2

f(g(x1))=x1

f(g(x2))=x2

f(g(x1))=f(g(x2)) iff x1=x2

Therefore (f o g)(x) are one-to-one

For part b I do not understand how to show it. I know it is true.