I keep getting “Bijective functions” questions wrong in Relations, Functions & Inverse Trigonometry. What's the trap?
trying to invert a function that maps two inputs to the same output.
The usual trap: trying to invert a function that maps two inputs to the same output. How to avoid it: only one-one AND onto functions can be reversed. Go back to the definition — a function has an inverse only if it is bijective — both one-one (injective) and onto (surjective).
Key point
Bijective functions
Common mistake
trying to invert a function that maps two inputs to the same output.
Memory tip
only one-one AND onto functions can be reversed.
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