If ƒ(a) = k, then which of the following must be true?

answer choices:

1. ƒ(k) = a
2. ƒ -1(k) = a
3. ƒ -1(a) = k

F(a)=k
means
when you input a, in f(x), you get k

lets see
1., this is false, unless f(x)=x which is not always true
2. this is the inverse, this is the sme function but input and output are switched
f(a)=k turns to f⁻¹(k)=a
true

3. this is true only if f(x)=x

2 is the right answer