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# Discrete Mathematics Questions and Answers – Functions

This section focuses on "Functions" in Discrete Mathematics. These Multiple Choice Questions (mcq) should be practiced to improve the Discrete Mathematics skills required for various interviews (campus interviews, walk-in interviews, company interviews), placements, entrance exams and other competitive examinations.

1. A function or mapping (Defined as f:X->Y) is a relationship from elements of one set X to elements of another set Y, then X is called?

A. Codomain
B. pre-image
C. Domain
D. image of function

2. A function can not be?

A. one to one
B. many to one
C. one to many.
D. All of the above

3. f:N->N,f(x)=5x is?

A. injective
B. not injective
C. surjective
D. inverse

4. A function f:A→B is ___________ (onto) if the image of f equals its range.

A. injective
B. surjective
C. inverse
D. not surjective

5. If function is both surjective and injective then it is known as?

A. invertible
B. composition
C. bijective
D. associative

6. If f and g are onto then the function (gof) is?

A. one to one
B. onto
C. one to many.
D. into

7. Composition does not hold?

A. associative property
B. commutative property
C. one-to-one function
D. Both A and B

8. Let f and g be the function from the set of integers to itself, defined by f(x) = 2x + 1 and g(x) = 3x + 4. Then the composition of f and g is ____________

A. 6x+9
B. 6x+7
C. 6x+3
D. 6x+8

9. __________ bytes are required to encode 2000 bits of data.

A. 4
B. 8
C. 1
D. 2

10. which of the following is true?

A. The function f(x) = x^3 is bijection from R to R.
B. The function f(x)=x+1 from the set of integers to itself is onto.
C. Both A and B
D. None of the above