Determine which functions are one-to-one.
I II
III
A)I only
B)I, II
C) I, II, III
D)II only
E)III only

Question

Determine which functions are one-to-one.
I  II 
III 
A)I only 
B)I, II 
C) I, II, III 
D)II only 
E)III only

Quizplus · Accepted Answer

A function is one-to-one if each element of the codomain corresponds to exactly one element of the domain. 
For function I, we have repeated outputs for different inputs, so it is not one-to-one. 
For function II, each input has a unique output, so it is one-to-one. 
For function III, we have repeated outputs for different inputs, so it is not one-to-one. 
Therefore, the only one-to-one function is II, so the answer is D.

Determine Which Functions Are One-To-One