Function is considered injective or one-to-one when:
A function is injective (one-to-one) when:
- A.
Each element in the domain has exactly one image in the codomain
- B.
Some distinct elements in the domain map to the same element in the codomain
- C.
Every element in the codomain has a pre-image in the domain
- D.
No two distinct elements in the domain map to the same element in the codomain
Attempted by 175 students.
Show answer & explanation
Correct answer: D
Correct answer: No two distinct elements in the domain map to the same element in the codomain.
In an injective function, different domain elements must have different images. In symbolic form, if f(a) = f(b), then a = b.
Why the first option is not enough: It only says that each input has exactly one output, which is true for every function. It does not guarantee that two different inputs cannot share that output.