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Relations & Functions · Question 77 of 125

Which of these describes this f from A to B?

Question 77

EasyOriginal question

$A = \{1, 2, 3, 4\}$ , $B = \{a, b, c, d, e\}$ , and $f : A \to B$ is $f = \{(1, a), (2, c), (3, e), (4, b)\}$ .

Which of these describes this $f$ from $A$ to $B$ ?

One-one but not ontoCorrect answerYour answerOne-one and ontoCorrect answerYour answerNeither one-one nor ontoCorrect answerYour answerOnto but not one-oneCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

The four images $a, c, e, b$ are all different: one-one.
$d$ is no element's image: not onto.

Worth noting

With 4 elements mapping into 5, at least one element of $B$ must be missed.

Concept: A function on a finite set
Typical timeTypical: 90 s
Your timeYours: —

The rule this testsOne-one functions

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