Question

If f(a)=K, then which of the following must be true?

f(K)=a
f inverse(k)=a
f inverse(a)=K

Answer 1

Properties of inverses:
If f(a)=K
then
1. f^-1(K)=a
2. f^-1(f(a))=a
... etc

None of the above answers is correct unless the second one says
f inverse(<b>K</b>)=a (i.e. uppercase K)

Answer 2

If ƒ(x ) = 2x, then ƒ -1(x ) =