Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

Match List-I with List-II.

List-I List-II
(A) $f(x)=\frac{1}{x}, R-\begin{Bmatrix}0 \end{Bmatrix}→R-\begin{Bmatrix}0 \end{Bmatrix}$ (I) neither injective nor subjective
(B) $f(x)=x^2, f: N →N$ (II) subjective but not injective
(C) $f(x)=x^2, f: R →R$ (III) injective but not surjective
(D) $f: \begin{Bmatrix}1, 2, 3 \end{Bmatrix}→\begin{Bmatrix}1, 2\end{Bmatrix}$defined as $f:\begin{Bmatrix} (1, 1), (2, 2), (3, 1)\end{Bmatrix}$ (IV) injective and surjective

Choose the correct answer from the options given below :

Options:

(A)-(IV), (B)-(I), (C)-(II), (D)-(III)

(A)-(III), (B)-(IV), (C)-(I), (D)-(II)

(A)-(II), (B)-(III), (C)-(IV), (D)-(I)

(A)-(IV), (B)-(III), (C)-(I), (D)-(II)

Correct Answer:

(A)-(IV), (B)-(III), (C)-(I), (D)-(II)

Explanation:

The correct answer is option (4) → (A)-(IV), (B)-(III), (C)-(I), (D)-(II)

(A) $f(x)=\frac{1}{x}$ so $f(x_1)=f(x_2)⇒x_1=x_2$

for every $f(x)$ there exist one x in $R-\{0\}$ (IV)

(B) $f(x)=x^2$, injective as $f:N→N$

But not surjective as eq. for $f(x)=7$ x doesn't exist (III)

(C) $f(x)=x^2$, for $f(x)=1$

$x=-1$ as well as 1 (Not injective)

for $f(x)=-4$

x doesn't exist (Not injective) (I)

(D) Not injective

as for $y = 1,x=1,3$

yes surjective as for every $y∈\{1,2\}$ there exists atleast one $x∈\{1,2,3\}$ (II)