MCQ
Let $A = \{ {x_1},\,{x_2},\,............,{x_7}\} $ and $B = \{ {y_1},\,{y_2},\,{y_3}\} $ be two sets containing seven and three distinct elements respectively. Then the total number of functions $f : A \to B$ that are onto, if there exist exactly three elements $x$ in $A$ such that $f(x)\, = y_2$, is equal to
  • $14.{}^7{C_3}$
  • B
    $16.{}^7{C_3}$
  • C
    $14.{}^7{C_2}$
  • D
    $12.{}^7{C_2}$

Answer

Correct option: A.
$14.{}^7{C_3}$
a
Number of onto function such that exactly three elements in $x \in A$ such that $f\left( x \right) = \frac{1}{2}$ is

equal to $ = {\,^7}{C_3},\left\{ {{2^4} - 2} \right\} = 14.{\,^7}{C_3}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Let $[\mathrm{t}]$ denote the greatest integer $\leq \mathrm{t}$. Then the value of $8 \cdot \int \limits_{-\frac{1}{2}}^{1}([2 x]+|x|) \,d x$ is .... .
If area bounded by the curves x = at2 and y = ax2 is 1, then a __________.
  1. $\frac{1}{2}$
  2. $\frac{1}{3}$
  3. $\frac{1}{\sqrt{3}}$
  4. $1$
Let $\vec{u}=2 \hat{i}-\hat{j}+\hat{k}, \vec{v}=-3 \hat{j}+2 \hat{k}$ be vectors in $R^3$ and $\vec{w}$ be a unit vector in the $X Y$-plane. Then, the
If A and B are matrices of order 3 × 2 and C is of order 2 × 3, then which of the following matrices is not defined:
  1. A+ B
  2. A+ BT
  3. A+ C
  4. B + CT
$f(x)$ and $g(x)$ are two differentiable function on $[0,\,2]$ such that , $f''(x) - g''(x) = 0,f'(1) = 2,g'(1) = 4$ ,$f(2) = 3$, $g(2) = 9,$ then $f(x) - g(x)$ at $x = 3/2$ is
Statement $- 1:$ The function $x^2 (e^x + e^{-x})$ is increasing for all $x > 0.$

Statement $-2:$ The functions $x^2e^x$ and $x^2e^{-x}$ are increasing for all $x > 0$ and the sum of two increasing functions in any interval $(a, b)$ is an increasing function in $(a, b).$

Let $\vec{a}=\hat{i}-\hat{j}+2 \hat{k}$ and $\vec{b}$ be a vector such that $\vec{a} \times \vec{b}=2 \hat{i}-\hat{k}$ and $\vec{a} \cdot \vec{b}=3$. Then the projection of $\vec{b}$ on the vector $\vec{a}-\vec{b}$ is :-
Let $A$ $\&$ $B$ are two independent events such that $P(A)+ P(B) = \frac{3}{4}$ $\&$ $P(\overline A /B) = \frac{2}{5},$ then $P(A \cap B)$ is -
Function $y=6-9 x-x^2$ is strictly increasing function on interval __________ .
If $\text{f(x)}=\text{a}|\sin\text{x}|+\text{be}^{|\text{x}|}+\text{c|x|}^3$and if f(x) is differentiable at x = 0, then:
  1. $\text{a}=\text{b}=\text{c}=0$
  2. $\text{a}=0,\text{b}=0;\text{c}\in\text{R}$
  3. $\text{b}=\text{c}=0,\text{a}\in\text{R}$
  4. $\text{c}=0,\text{a}=0,\text{b}\in\text{R}$