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
View Answer
Ans : C
Explanation: A function or mapping (Defined as f:X->Y) is a relationship from elements of one set X to elements of another set Y (X and Y are non-empty sets). X is called Domain
2. A function can not be?
A. one to one
B. many to one
C. one to many.
D. All of the above
View Answer
Ans : C
Explanation: A function can be one to one or many to one but not one to many.
3. f:N->N,f(x)=5x is?
A. injective
B. not injective
C. surjective
D. inverse
View Answer
Ans : A
Explanation: f:N->N,f(x)=5x is injective.
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
View Answer
Ans : B
Explanation: A function f:A->B is surjective (onto) if the image of f equals its range.
5. If function is both surjective and injective then it is known as?
A. invertible
B. composition
C. bijective
D. associative
View Answer
Ans : C
Explanation: f is both surjective and injective, we can say f is bijective.
6. If f and g are onto then the function (gof) is?
A. one to one
B. onto
C. one to many.
D. into
View Answer
Ans : B
Explanation: If f and g are onto then the function (gof) is also onto.
7. Composition does not hold?
A. associative property
B. commutative property
C. one-to-one function
D. Both A and B
View Answer
Ans : B
Explanation: Composition always holds associative property but does not hold commutative property.
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
View Answer
Ans : A
Explanation: The composition of f and g is given by f(g(x)) which is equal to 2(3x + 4) + 1
9. __________ bytes are required to encode 2000 bits of data.
A. 4
B. 8
C. 1
D. 2
View Answer
Ans : D
Explanation: Two bytes are required to encode 2000 (actually with 2 bytes you can encode up to and including 65,535.
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
View Answer
Ans : C
Explanation: Both A and B the following is true.
Discussion