- #1
Esran
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- 0
Let f:X->Y and g:Y->Z be functions. Suppose A is a subset of Z. I'm wondering whether (g o f)-1(A)=f-1(g-1(A)).
I'm lost as to where to go with this problem. I know I need to do something using images, but manipulating the inverses of composite functions is proving to be very confusing; I don't know how to properly translate these functions into terms that match up with my definitions, which are as follows:
1) Let f:X->Y be a function: for a subset A of X, the set f(A)={y in Y: y=f(x) for some x in A}.
2) For a subset C of Y, the set f-1(C) = {x in X: f(x) is in C}.
Can you please point me in the right direction? I'm sure that if I could just grasp how to prove this theorem, I'd understand inverses so much better.
Thank you for your time!
I'm lost as to where to go with this problem. I know I need to do something using images, but manipulating the inverses of composite functions is proving to be very confusing; I don't know how to properly translate these functions into terms that match up with my definitions, which are as follows:
1) Let f:X->Y be a function: for a subset A of X, the set f(A)={y in Y: y=f(x) for some x in A}.
2) For a subset C of Y, the set f-1(C) = {x in X: f(x) is in C}.
Can you please point me in the right direction? I'm sure that if I could just grasp how to prove this theorem, I'd understand inverses so much better.
Thank you for your time!