# Math VVI Objective Question Bihar Board |12th Math Objective Question Bihar Board |Math Objective Question Bihar Board |12th Math Bseb

1. In the set of all straight lines in a plane, the relation R “to be
Perpendicular” is-

(a) Reflexive and transitive

(b) Symmetric and transitive

(c) Symmetric

(d) None of these

Ans: (c) Symmetric

Explanation :

If line L1 is perpendicular to the line L₂ , then L₂ will also be

perpendicular to L1

If (L1, L₂) = R⇒(L₂, L1)€R

Hence, R is symmetric.

2. f: A→B will be an onto function if-

(a) f(A) C B

(b) f(A) = B

(c) f(A) )B

(d) f(A) € B

Ans: (b)-f(A) = B

Explanation :

A function is said to be onto iff Range of function is equal to co-domain of the function

.f: A B is onto iff f(A) = B

3. If f(x1) = f(x₂) ⇒ x1=x₂V, x₂६A, then what type of a function

if f: A – B ?

(a) One-one

(b) Constant

(c) Onto

(d) Many one

Ans: (a) One-one

Explanation:

If, f(x1) = f(x₂)

X1= x₂, then f(x) is one-one.

4. The operation is defined as a * b = 2a + b, then (2 * 5) * 4 is.

(a) 18

(b) 17

(c) 19

(d) 21

Ans: (a) 18

Explanation

We have,

a*b=2a+b

(2*3)*4 = (2×2+3)*4 = 7*4

= 2 × 7+4 = 18

5. Let A = {1,2,3}, which of the following function f: A → A does not have an inverse function?

(a) {(1,1),(2,2), (3,3)}

(b) {(1,2), (2,1), (3,1)}

(c) {(1,3), (3,2), (2,1)}

(d) {(1,2), (2,3), (3,1)}

Ans: (b) {(1,2), (2,1),(3,1)}

Explanation:

Any function will be an invertible function, when function is one-one and onto.

Check option (a)

Check one one :

f = {(1,1),(2,2), (3,3)}

Since each element has unique image, f is one-one. Check onto:

Since for every image, there is a corresponding

Thus f is onto.

Since function is both one-one and onto It will have inverse

f = {(1,1),(2,2), (3,3)}

f’ = {(1,1),(2,2,),(3,3)}

Check option (b)

element,

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