Exam-style question
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If f: A → B and g: B → C, what is the co-domain of g ○ f?.
- A.A
- B.B
- C.C
- D.B → C
Model answer
What a good answer should say
- C
Explanation
Why this works
The composition starts with an input from A and produces the final output of g, whose co-domain is C. Therefore, g ○ f has co-domain C.
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